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 A131819 #9 Mar 04 2022 01:26:02
%S A131819 1,4,2,8,5,3,13,9,7,4,19,14,12,9,5,26,20,18,15,11,6,34,27,25,22,18,13,
%T A131819 7,43,35,33,30,26,21,15,8,53,44,42,39,35,30,24,17,9,64,54,52,49,45,40,
%U A131819 34,27,19,10,76,65,63,60,56,51,45,38,30,21,11
%N A131819 A131818 * A000012 as infinite lower triangular matrices. Triangle read by rows, partial sums starting from the right of A131818.
%C A131819 Left column = A034856: (1, 4, 8, 13, 19, 26, 34, ...). Row sums = A131820: (1, 6, 16, 33, 59, 96, ...).
%e A131819 First few rows of the triangle:
%e A131819 1;
%e A131819 4, 2;
%e A131819 8, 5, 3;
%e A131819 13, 9, 7, 4;
%e A131819 19, 14, 12, 9, 5;
%e A131819 26, 20, 18, 15, 11, 6;
%e A131819 34, 27, 25, 22, 18, 13, 7;
%e A131819 ...
%o A131819 (PARI) tabl(nn) = {m131818 = matrix(nn, nn, n, k, if (k==1, n, if (k <= n, k, 0))); m000012 = matrix(nn, nn, n, k, (k<=n)); m131819 = m131818 * m000012; for (n = 1, nn, for (k = 1, n, print1(m131819[n, k], ", ");););} \\ _Michel Marcus_, Feb 12 2014
%Y A131819 Cf. A131818, A000012, A131820, A034856.
%K A131819 nonn,tabl
%O A131819 1,2
%A A131819 _Gary W. Adamson_, Jul 18 2007
%E A131819 More terms from _Michel Marcus_, Feb 12 2014