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 A003026 M4666 #17 Dec 27 2021 23:42:18 %S A003026 1,9,198,10710,1384335,416990763,286992935964,444374705175516, %T A003026 1528973599758889005,11573608032229769067465, %U A003026 191141381932394665770442818,6839625961762363728765713227698 %N A003026 Number of n-node labeled acyclic digraphs with 2 out-points. %D A003026 R. W. Robinson, Counting labeled acyclic digraphs, pp. 239-273 of F. Harary, editor, New Directions in the Theory of Graphs. Academic Press, NY, 1973. %D A003026 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A003026 Andrew Howroyd, <a href="/A003026/b003026.txt">Table of n, a(n) for n = 2..50</a> %o A003026 (PARI) \\ requires A058876. %o A003026 my(T=A058876(20)); vector(#T-1, n, T[n+1][2]) \\ _Andrew Howroyd_, Dec 27 2021 %Y A003026 A diagonal of A058876. %Y A003026 Cf. A003025. %K A003026 nonn %O A003026 2,2 %A A003026 _N. J. A. Sloane_ %E A003026 More terms from _Vladeta Jovovic_, Apr 10 2001