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 A129620 #21 Oct 23 2019 14:43:08 %S A129620 1,1,0,1,1,0,1,2,1,0,1,2,5,1,0,1,2,8,9,1,0,1,2,8,24,17,1,0,1,2,8,32, %T A129620 74,26,1,0,1,2,8,32,140,189,41,1,0,1,2,8,32,167,542,460,57,1,0,1,2,8, %U A129620 32,167,837,1964,989,81,1,0,1,2,8,32,167,928,4167,6291,2021,106,1,0 %N A129620 Square array read by falling antidiagonals: T(n,k) is the number of connected directed multigraphs with loops with n arcs and at most k vertices. %C A129620 Partial sums of the rows of A139621, i.e., T(n,k) = sum(A139621(n,p),p=0..k). %H A129620 Andrew Howroyd, <a href="/A129620/b129620.txt">Table of n, a(n) for n = 0..1325</a> %F A129620 T(n,2) = A138107(n,2) - floor(n/2). %F A129620 If k >= n+1, T(n,k) = A137975(n). %e A129620 1 1 1 1 1 1 ... %e A129620 0 1 2 2 2 2 ... %e A129620 0 1 5 8 8 8 ... %e A129620 0 1 9 24 32 32 ... %e A129620 0 1 17 (...) %e A129620 (...) %Y A129620 Cf. A138107, A139621. %K A129620 nonn,tabl %O A129620 0,8 %A A129620 _Benoit Jubin_, May 06 2008 %E A129620 Name edited by _M. F. Hasler_, Jul 31 2017 %E A129620 Terms a(32) and beyond from _Andrew Howroyd_, Oct 22 2019