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 A293718 #25 Oct 16 2017 12:55:28 %S A293718 1,1,1,1,1,1,1,1,5,1,1,1,5,13,1,1,1,5,31,73,1,1,1,5,31,145,281,1,1,1, %T A293718 5,31,241,1181,1741,1,1,1,5,31,241,1661,9661,8485,1,1,1,5,31,241,2261, %U A293718 16861,77155,57233,1,1,1,5,31,241,2261,20461,181315,794081 %N A293718 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of e.g.f. exp(Sum_{j=1..k} j*x^j). %H A293718 Seiichi Manyama, <a href="/A293718/b293718.txt">Antidiagonals n = 0..139, flattened</a> %F A293718 A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..min(k,n)} j^2*A(n-j,k)/(n-j)!. %e A293718 Square array begins: %e A293718 1, 1, 1, 1, 1, ... %e A293718 1, 1, 1, 1, 1, ... %e A293718 1, 5, 5, 5, 5, ... %e A293718 1, 13, 31, 31, 31, ... %e A293718 1, 73, 145, 241, 241, ... %e A293718 1, 281, 1181, 1661, 2261, ... %Y A293718 Columns k=1..4 give A000012, A115329, A293716, A293717. %Y A293718 Rows n=0-1 give A000012. %Y A293718 Main diagonal gives A082579. %Y A293718 Cf. A293669, A293724. %K A293718 nonn,tabl %O A293718 0,9 %A A293718 _Seiichi Manyama_, Oct 15 2017