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 A131226 #11 Jun 07 2023 08:41:51 %S A131226 1,3,4,1,6,7,3,4,9,10,1,6,7,12,13,3,4,9,10,15,16,1,6,7,12,13,18,19,3, %T A131226 4,9,10,15,16,21,22,1,6,7,12,13,18,19,24,25,3,4,9,10,15,16,21,22,27, %U A131226 28,1,6,7,12,13,18,19,24,25,30,31,3,4,9,10,15,16,21,22,27,28,33,34 %N A131226 Triangle read by rows: 3*A002260 - 2*A128174 as infinite lower triangular matrices. %C A131226 Row sums = A095894: (1, 7, 14, 26, 39, 57, ...). %C A131226 A131225 = 2*A002260 - A128174. %e A131226 First few rows of the triangle: %e A131226 1; %e A131226 3, 4; %e A131226 1, 6, 7; %e A131226 3, 4, 9, 10; %e A131226 1, 6, 7, 12, 13; %e A131226 3, 4, 9, 10, 15, 16; %e A131226 1, 6, 7, 12, 13, 18, 19; %e A131226 ... %Y A131226 Cf. A002260, A095894, A128174, A131225. %K A131226 nonn,tabl %O A131226 1,2 %A A131226 _Gary W. Adamson_, Jun 20 2007 %E A131226 a(47), a(49) corrected and more terms from _Georg Fischer_, Jun 07 2023