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 A134248 #6 Mar 25 2022 00:36:02 %S A134248 1,2,1,4,5,1,7,15,9,1,11,34,36,14,1,16,65,100,70,20,1,22,111,225,230, %T A134248 120,27,129,175,441,595,455,189,35,1,37,260,784,1316,1330,812,280,44, %U A134248 1,46,369,1296,2604,3276,2646,1344,396,54,1 %N A134248 M * A007318, M = a triangle by rows, n-th row = (n-1) zeros followed by T(n), 1. %C A134248 Row sums = A104270: (1, 3, 10, 32, 96, 172, ...). %C A134248 Left column = A000124. %F A134248 M * A007318, where M = an infinite lower triangular matrix with rows: n-th row = (n-1) zeros followed by T(n), 1; T(n) = n-th triangular number. M = an infinite lower triangular matrix with (1,1,1,...) in the main diagonal and the triangular series in the subdiagonal. %e A134248 First few rows of the triangle: %e A134248 1; %e A134248 2, 1; %e A134248 4, 5, 1; %e A134248 7, 15, 9, 1; %e A134248 11, 34, 36, 14, 1; %e A134248 16, 65, 100, 70, 20, 1; %e A134248 ... %Y A134248 Cf. A104270, A000124, A000217. %K A134248 nonn,tabl %O A134248 0,2 %A A134248 _Gary W. Adamson_, Oct 15 2007