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 A131782 #12 Jun 05 2023 05:22:31 %S A131782 1,5,1,11,5,1,19,11,5,1,29,19,11,5,1,41,29,19,11,5,1,55,41,29,19,11,5, %T A131782 1,71,55,41,29,19,11,5,1,89,71,55,41,29,19,11,5,1,109,89,71,55,41,29, %U A131782 19,11,5,1,131,109,89,71,55,41,29,19,11,5,1,155,131,109,89,71,55,41,29,19,11,5,1 %N A131782 Triangle read by rows: (A004736 * A000012) + (A000012 * A004736) - A000012 as infinite lower triangular matrices. %C A131782 Row sums = A084990 starting (1, 6, 17, 36, 65, 106, ...). %F A131782 n-th row = n descending terms of A028387: (1, 5, 11, 19, 29, 41, 55, ...). By columns, each column = A028387: (1, 5, 11, 19, 29, ...). %e A131782 First few rows of the triangle: %e A131782 1; %e A131782 5, 1; %e A131782 11, 5, 1; %e A131782 19, 11, 5, 1; %e A131782 29, 19, 11, 5, 1; %e A131782 41, 29, 19, 11, 5, 1; %e A131782 55, 41, 29, 19, 11, 5, 1; %e A131782 ... %Y A131782 Cf. A004736, A028387, A084990. %K A131782 nonn,tabl %O A131782 1,2 %A A131782 _Gary W. Adamson_, Jul 14 2007 %E A131782 Sign in definition and a(41) corrected; more terms from _Georg Fischer_, Jun 05 2023