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 A054943 #18 Sep 11 2018 00:11:34
%S A054943 0,2,8,320,27584,6991360,5179178368,11396324458496,74944172892993536,
%T A054943 1476405354971707604992,87208352627656970712229888,
%U A054943 15450530398306943408625302896640,8211400756816955708062672318337859584
%N A054943 Number of connected oriented graphs on n nodes with an odd number of edges.
%H A054943 Andrew Howroyd, <a href="/A054943/b054943.txt">Table of n, a(n) for n = 1..50</a>
%H A054943 V. A. Liskovets, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL3/LISK/Derseq.html">Some easily derivable sequences</a>, J. Integer Sequences, 3 (2000), #00.2.2.
%F A054943 a(n) = (A054941(n) + (-1)^n*A000831(n-1))/2. - _Andrew Howroyd_, Sep 10 2018
%t A054943 nn = 15; g[z] :=Sum[(1 + 2 u)^Binomial[n, 2] z^n/n!, {n, 0, nn}]; Drop[
%t A054943 Map[Total[#[[2 ;; Binomial[nn, 2] + 1 ;;2]]]&,Range[0,nn]!CoefficientList[
%t A054943 Series[Log[g[z]], {z, 0, nn}], {z, u}]], 1] (* _Geoffrey Critzer_, Jul 28 2016 *)
%o A054943 (PARI) seq(n)={my(A=O(x*x^n)); Vec(serlaplace(log(sum(k=0, n, 3^binomial(k, 2)*x^k/k!) + A) - log(cos(x + A) + sin(x + A)))/2, -n)} \\ _Andrew Howroyd_, Sep 10 2018
%Y A054943 Cf. A000831, A054941, A054942.
%K A054943 nonn,easy
%O A054943 1,2
%A A054943 _N. J. A. Sloane_, May 24 2000
%E A054943 More terms from _Vladeta Jovovic_, Mar 11 2003