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 A139628 #2 Mar 31 2012 10:31:22 %S A139628 1,2,9,33 %N A139628 Row sums of A139623, number of directed multigraphs with loops and no vertex of degree 0, with n arcs, which are transitive (the existence of a path between two points implies the existence of an arc between those two points). %Y A139628 Cf. A139629, A139630. %K A139628 more,nonn %O A139628 0,2 %A A139628 _Benoit Jubin_, May 01 2008