This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A123549 #11 Sep 02 2019 05:23:44 %S A123549 1,1,2,7,36,265,3039,56532,1795771,100752242,10189358360, %T A123549 1879720735880,637617233537026,400169631647375590, %U A123549 467115844246503901102,1018822456144128438039598,4169121243929999956903622399,32126195519194538601647462868271 %N A123549 Number of unlabeled connected bicolored graphs on 2n nodes which are invariant when the two color classes are interchanged. %D A123549 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978. %F A123549 a(n) = 2*A005142(2*n) - A318870(2*n). - _Andrew Howroyd_, Sep 04 2018 %t A123549 A005142 = Import["https://oeis.org/A005142/b005142.txt", "Table"][[All, 2]]; %t A123549 A318870 = Import["https://oeis.org/A318870/b318870.txt", "Table"][[All, 2]]; %t A123549 a[n_] := 2*A005142[[2*n + 1]] - A318870[[2*n + 1]]; %t A123549 a /@ Range[0, 17] (* _Jean-François Alcover_, Sep 02 2019 *) %Y A123549 Row sums of A123550. %Y A123549 Cf. A005142, A318869, A318870. %K A123549 nonn %O A123549 0,3 %A A123549 _N. J. A. Sloane_, Nov 14 2006 %E A123549 a(0)=1 prepended and terms a(8) and beyond from _Andrew Howroyd_, Sep 04 2018