For n = 1 :
'@': 0 edges; 1/1 good signs.
For n = 2 :
'A_': 1 edges; 1/1 good signs.
For n = 3 :
'BW': 2 edges; 1/1 good signs.
'Bw': 3 edges; 1/1 good signs.
For n = 4 :
'CF': 3 edges; 1/1 good signs.
'CV': 4 edges; 1/1 good signs.
'C]': 4 edges; 2/2 good signs.
'C^': 5 edges; 2/2 good signs.
'C~': 6 edges; 4/4 good signs.
For n = 5 :
'DEw': 5 edges; 1/2 good signs.
'DFw': 6 edges; 4/4 good signs.
'DUW': 5 edges; 1/1 good signs.
'DUw': 6 edges; 2/2 good signs.
'DTw': 6 edges; 1/2 good signs.
'D]w': 7 edges; 4/4 good signs.
For n = 6 :
'E?zO': 6 edges; 1/2 good signs.
'ECxo': 7 edges; 2/2 good signs.
'EEr_': 7 edges; 1/4 good signs.
'EEh_': 6 edges; 1/2 good signs.
'EEj_': 7 edges; 3/4 good signs.
'EEho': 7 edges; 1/2 good signs.
'EEiW': 7 edges; 1/2 good signs.
'EEz_': 8 edges; 7/8 good signs.
'EEzO': 8 edges; 1/4 good signs.
'EFz_': 9 edges; 16/16 good signs.
'EQzO': 8 edges; 2/4 good signs.
'EUZ_': 8 edges; 4/4 good signs.
'EUZO': 8 edges; 4/4 good signs.
'EUxo': 9 edges; 8/8 good signs.
For n = 7 :
'F?re_': 8 edges; 0/4 good signs.
'F?qr_': 8 edges; 1/4 good signs.
'FCR`o': 8 edges; 1/2 good signs.
'FCpv?': 9 edges; 3/4 good signs.
'FCptO': 9 edges; 4/4 good signs.
'FCZf?': 9 edges; 2/8 good signs.
'FCZb_': 9 edges; 1/4 good signs.
'FCZco': 9 edges; 1/4 good signs.
'FCxv?': 10 edges; 8/8 good signs.
'FEhf?': 9 edges; 7/8 good signs.
'FEhe_': 9 edges; 1/4 good signs.
'FEhd_': 9 edges; 2/4 good signs.
'FEhv?': 10 edges; 7/8 good signs.
'FEhuO': 10 edges; 8/8 good signs.
'FQjR_': 10 edges; 2/8 good signs.
For n = 8 :
'G?`vF?': 10 edges; 1/8 good signs.
'G?qbe_': 10 edges; 1/8 good signs.
'G?qb_w': 10 edges; 1/4 good signs.
'G?q`qg': 10 edges; 1/4 good signs.
'G?ovE_': 10 edges; 1/8 good signs.
'G?opuG': 10 edges; 1/8 good signs.
'G?qrf?': 11 edges; 6/16 good signs.
'G?qrd_': 11 edges; 7/16 good signs.
'G?zTb_': 12 edges; 31/32 good signs.
'GCOfF?': 9 edges; 0/4 good signs.
'GCOf?w': 9 edges; 0/4 good signs.
'GCQbb_': 10 edges; 1/4 good signs.
'GCQbcW': 10 edges; 1/4 good signs.
'GCR`v?': 11 edges; 6/8 good signs.
'GCR`u_': 11 edges; 5/8 good signs.
'GCR`r_': 11 edges; 4/8 good signs.
'GCpdao': 11 edges; 2/8 good signs.
'GCpd`o': 11 edges; 1/8 good signs.
'GCpdag': 11 edges; 4/8 good signs.
'GCpbd_': 11 edges; 3/8 good signs.
'GCpbdO': 11 edges; 2/8 good signs.
'GCrb`o': 12 edges; 16/16 good signs.
'GCXed_': 11 edges; 1/8 good signs.
'GCXecW': 11 edges; 1/8 good signs.
'GCZJd_': 12 edges; 13/16 good signs.
'GCXmd_': 12 edges; 2/16 good signs.
'GCY^B_': 12 edges; 16/16 good signs.
For n = 9 :
'H?`adao': 11 edges; 1/8 good signs.
'H?`ad_M': 11 edges; 1/8 good signs.
'H?`ed`g': 12 edges; 0/8 good signs.
'H?`e`rC': 12 edges; 1/8 good signs.
'H?`e`qK': 12 edges; 1/8 good signs.
'H?`cZb_': 12 edges; 1/8 good signs.
'H?`vAqo': 13 edges; 4/16 good signs.
'H?r@d`o': 12 edges; 1/16 good signs.
'H?qad`o': 12 edges; 3/16 good signs.
'H?qad`g': 12 edges; 1/8 good signs.
'H?qacha': 12 edges; 1/8 good signs.
'H?ovE_w': 13 edges; 2/16 good signs.
'H?ouT`o': 13 edges; 1/16 good signs.
'H?otU`S': 13 edges; 3/16 good signs.
'HCOf@pS': 12 edges; 1/8 good signs.
'HCOf?z_': 12 edges; 6/16 good signs.
'HCOf?xo': 12 edges; 1/8 good signs.
'HCQf@pS': 13 edges; 4/16 good signs.
'HCQf@o[': 13 edges; 9/16 good signs.
'HCQe`pg': 13 edges; 2/16 good signs.
'HCQe`pc': 13 edges; 3/16 good signs.
'HCQb`rG': 13 edges; 4/16 good signs.
'HCQeHow': 13 edges; 7/16 good signs.
For n = 10 :
'I??FCpSJ?': 12 edges; 1/8 good signs.
'I?B@dPgs?': 13 edges; 0/16 good signs.
'I?B@dPWB_': 13 edges; 1/8 good signs.
'I?B@`jGo_': 13 edges; 1/16 good signs.
'I?BDeOw[?': 14 edges; 1/32 good signs.
'I?BDdPW[?': 14 edges; 6/32 good signs.
'I?B@t`ge?': 14 edges; 2/32 good signs.
'I?B@pr_s?': 14 edges; 1/32 good signs.
'I?BEL_w[?': 14 edges; 1/16 good signs.
'I?BeeOwM?': 15 edges; 18/64 good signs.
'I?Bcu`gM?': 15 edges; 33/64 good signs.
'I?`@eCkF?': 13 edges; 0/16 good signs.
'I?`Df?[L?': 14 edges; 2/16 good signs.
'I?`Db_kF?': 14 edges; 2/16 good signs.
'I?bFB_wF?': 15 edges; 11/32 good signs.
'I?`ad_w`_': 14 edges; 1/16 good signs.
'I?`aeQoM?': 14 edges; 0/16 good signs.
'I?`aeQoF?': 14 edges; 0/16 good signs.
'I?`adGwc_': 14 edges; 1/16 good signs.
'I?`acgwg_': 14 edges; 2/16 good signs.
'I?`acgiw?': 14 edges; 0/16 good signs.
'I?`bfAWF?': 15 edges; 1/32 good signs.
'I?`cm`gM?': 15 edges; 14/32 good signs.
'I?`cmPoM?': 15 edges; 5/32 good signs.
'I?`amQoM?': 15 edges; 2/32 good signs.
'I?`c]`oM?': 15 edges; 1/32 good signs.
'ICOfBaKF?': 15 edges; 17/32 good signs.
'ICOf@pSb?': 15 edges; 32/32 good signs.
'ICOedPKL?': 15 edges; 1/32 good signs.
'ICOedO[X?': 15 edges; 4/32 good signs.
For n = 11 :
'J?AB?rOi?M?': 14 edges; 0/16 good signs.
'J?ABCqW[BO?': 15 edges; 1/32 good signs.
'J?ABAqWL@W?': 15 edges; 1/16 good signs.
'J?BD?o[WOs?': 15 edges; 1/32 good signs.
'J?B@cXgUD_?': 16 edges; 1/32 good signs.
'J?`@EaoBb_?': 15 edges; 1/32 good signs.
'J?`D@bOBR_?': 15 edges; 0/32 good signs.
'J?`D@bOBRO?': 15 edges; 0/16 good signs.
'J?`D@pgd?k?': 16 edges; 1/32 good signs.
'J?`@`b_Be_?': 15 edges; 0/32 good signs.
'J?`@fBOJ?w?': 16 edges; 1/32 good signs.
'J?`@f?keAg?': 16 edges; 0/32 good signs.
'J?`@f?kUCg?': 16 edges; 2/32 good signs.
'J?`@eDgL?w?': 16 edges; 1/32 good signs.
For n = 12 :
'K??CB`gXCoR?': 16 edges; 1/32 good signs.
'K??E@agXAoQ_': 16 edges; 0/32 good signs.
'K??E@aKJAoI_': 16 edges; 1/32 good signs.
'K??EDagLAWI_': 17 edges; 2/64 good signs.
'K??EDaKMBGJ?': 17 edges; 0/64 good signs.
'K??E@qcX?wY?': 17 edges; 1/64 good signs.
'K??FEbGL@WB_': 18 edges; 1/128 good signs.
'K??FEagT@WB_': 18 edges; 10/128 good signs.
'K??FEaKY@gB_': 18 edges; 8/128 good signs.
'K??FEaKR@oE_': 18 edges; 18/128 good signs.
'K?AEB`gHcoB_': 18 edges; 1/64 good signs.
'K?AB?rOLDOH_': 17 edges; 1/32 good signs.
'K?ABEagE`gH_': 18 edges; 4/64 good signs.
'K?ABCfGT@oD_': 18 edges; 6/64 good signs.
'K?`@?b_s?U?w': 16 edges; 1/32 good signs.
'K?`@E`gh?sAo': 18 edges; 0/64 good signs.
'K?`@E`gFCKEO': 18 edges; 1/64 good signs.
'K?`@E`gEcKE_': 18 edges; 0/64 good signs.
'K?`@Cr_T?[EO': 18 edges; 0/64 good signs.
For n = 13 :
'L??E@_KiAoK_d?': 18 edges; 1/64 good signs.
'L??E@agX?[J?d?': 19 edges; 1/64 good signs.
'L?AA@_geAo?w@g': 18 edges; 0/64 good signs.
'L?`@?b_s@W@W@o': 19 edges; 1/64 good signs.
For n = 14 :
'M???EAob@SM?D_R??': 20 edges; 1/128 good signs.
'M???EAob@SL?D_T??': 20 edges; 0/128 good signs.
'M???EAob@SJ?D_X??': 20 edges; 0/128 good signs.
'M???FBObBCD_E_D_?': 21 edges; 0/256 good signs.
'M???FBObASF?H_D_?': 21 edges; 2/256 good signs.
'M???FBObASD_D_K_?': 21 edges; 0/256 good signs.
'M???FAW`agD_K_Q_?': 21 edges; 0/256 good signs.
'M?AAD?WsAQEOB_HG?': 21 edges; 1/128 good signs.
For 15 vertices:
For 16 vertices:
'O????B_sCWGWI_E_Cg?i?': 24 edges; 0/512 good signs.
'O????B_eCKIGL?R?CW?U?': 24 edges; 1/512 good signs.
'O????B_eCKIGL?Q_@g@E?': 24 edges; 0/512 good signs.
For 17 vertices:
For 18 vertices:
'Q??????wCoOoSOPG@g@E?IG?Q_?': 27 edges; 0/1024 good signs.
For 19 vertices:
For 20 vertices:
Exception MemoryError: MemoryError() in <object repr() failed> ignored
Exception MemoryError: MemoryError() in <generator object nauty_geng at 0x7fbfcc77efa0> ignored
Traceback (most recent call last):            lens = (A + 1)^3 + 2
  File "", line 1, in <module>
    
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/graph.py", line 1590, in _recursive_spanning_trees
    trees.extend(_recursive_spanning_trees(G,forest))
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/graph.py", line 1573, in _recursive_spanning_trees
    trees = _recursive_spanning_trees(G,forest)
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/graph.py", line 1590, in _recursive_spanning_trees
    trees.extend(_recursive_spanning_trees(G,forest))
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/graph.py", line 1564, in _recursive_spanning_trees
    return [forest.copy()]
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/generic_graph.py", line 1086, in copy
    data_structure=data_structure)
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/graph.py", line 1180, in __init__
    self.add_edges(data.edge_iterator(), loops=loops)
  File "/home/sage/build/sage-8.1/local/lib/python2.7/site-packages/sage/graphs/generic_graph.py", line 10499, in add_edges
    self._backend.add_edge(u, v, label, self._directed)
MemoryError: failed to allocate 32 bytes
no mem for new parser
MemoryError