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 A055969 #11 Sep 12 2019 09:40:39
%S A055969 0,1,6,104,4736,770112,440994608,896679244544,6513978322585408,
%T A055969 170630215971902124288,16261454692523251085611648,
%U A055969 5683372715412699486531047331840,7334542846356464931239079919515090432,35157828307617499760690834338506768579289088
%N A055969 Number of unlabeled digraphs with n nodes and an odd number of arcs.
%H A055969 Andrew Howroyd, <a href="/A055969/b055969.txt">Table of n, a(n) for n = 1..50</a>
%F A055969 a(n) = (A000273(n)-A003086(n))/2.
%t A055969 A000273 = Cases[Import["https://oeis.org/A000273/b000273.txt", "Table"], {_, _}][[All, 2]];
%t A055969 A003086 = Cases[Import["https://oeis.org/A003086/b003086.txt", "Table"], {_, _}][[All, 2]];
%t A055969 a[n_] := (A000273[[n + 1]] - A003086[[n]])/2;
%t A055969 Array[a, 50] (* _Jean-François Alcover_, Sep 12 2019, after _Andrew Howroyd_ *)
%Y A055969 Cf. A054928, A007869, A054960.
%K A055969 easy,nonn
%O A055969 1,3
%A A055969 _Vladeta Jovovic_, Jul 19 2000
%E A055969 Terms a(14) and beyond from _Andrew Howroyd_, Sep 17 2018