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 A112692 #7 Aug 29 2019 17:32:10 %S A112692 1,3,-1,-6,6,-9,-70,163,-42,-72,30,-123,-1110,8440,-18244,2423,43036, %T A112692 -53172,11232,8640,90,-792,-7425,137760,-771911,1624514,2262109, %U A112692 -21114844,51074797,-54783526,6214788,45596664,-40513824,7309440,3110400,630,-10278,-86841,3685605,-41159454 %N A112692 Coefficient array of numerator polynomials of o.g.f.s (rising powers) for the columns of triangle A008517 (second-order Eulerian numbers). %C A112692 The sequence of row lengths is A000217 (triangular numbers): [1, 3, 6, 10, 15, 21,..]. %C A112692 The o.g.f. of the k-th column sequence of triangle A008517(n,k), n>=k>=1, is (2^floor(k/2))*(x^k)*p(k,x)/product((1-j*x)^(k+1-j),j=1..k), k>=2, with the row polynomials p(k,x):= sum(a(k-2,m)*x^m,m=0..(k*(k-1)/2)-1). %H A112692 W. Lang, <a href="/A112692/a112692.txt">First ten rows.</a> %e A112692 Rows: [1]; [3,-1,-6]; [6,-9,-70,163,-42,-72];... %e A112692 The k=3, offset 3, column sequence [6,58,328,..] of A008517 has o.g.f. 2*(x^3)*(3-x-6*x^2)/product((1-j*x)^(4-j),j=1..3). %Y A112692 Row sums A112693. Unsigned row sums A112694. %K A112692 sign,easy,tabf %O A112692 0,2 %A A112692 _Wolfdieter Lang_, Oct 14 2005