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 A334561 #19 May 09 2020 02:41:34 %S A334561 1,1,-1,1,-1,1,1,-1,-1,-1,1,-1,-1,5,1,1,-1,-1,-1,1,-1,1,-1,-1,-1,25, %T A334561 -41,1,1,-1,-1,-1,1,19,31,-1,1,-1,-1,-1,1,139,-209,461,1,1,-1,-1,-1,1, %U A334561 19,151,-2269,-895,-1,1,-1,-1,-1,1,19,871,-1429,2801,-6481,1,1,-1,-1,-1,1,19,151,1091,-19039,68615,22591,-1 %N A334561 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals downwards, where column k is the expansion of e.g.f. exp(-Sum_{j=1..k} x^j). %H A334561 Seiichi Manyama, <a href="/A334561/b334561.txt">Antidiagonals n = 0..139, flattened</a> %F A334561 A(0,k) = 1 and A(n,k) = - (n-1)! * Sum_{j=1..min(k,n)} j*A(n-j,k)/(n-j)!. %e A334561 Square array begins: %e A334561 1, 1, 1, 1, 1, 1, 1, ... %e A334561 -1, -1, -1, -1, -1, -1, -1, ... %e A334561 1, -1, -1, -1, -1, -1, -1, ... %e A334561 -1, 5, -1, -1, -1, -1, -1, ... %e A334561 1, 1, 25, 1, 1, 1, 1, ... %e A334561 -1, -41, 19, 139, 19, 19, 19, ... %e A334561 1, 31, -209, 151, 871, 151, 151, ... %Y A334561 Columns k=1..5 give A033999, A000321, A334562, A334564, A334565. %Y A334561 Main diagonal gives A293116. %Y A334561 Cf. A293669, A334568. %K A334561 sign,tabl %O A334561 0,14 %A A334561 _Seiichi Manyama_, May 06 2020