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 A127780 #4 Feb 14 2022 23:38:27 %S A127780 1,3,6,5,10,15,7,14,21,28,9,18,27,36,45,11,22,33,44,55,66,13,26,39,52, %T A127780 65,78,91,15,30,45,60,75,90,105,120 %N A127780 A127775 * A002260 as infinite lower triangular matrices. %C A127780 Odd number transform of A002260. %C A127780 Row sums = A002414: (1, 9, 30, 70, 135, ...). %e A127780 First few rows of the triangle: %e A127780 1; %e A127780 3, 6; %e A127780 5, 10, 15; %e A127780 7, 14, 21, 28; %e A127780 9, 18, 27, 36, 45; %e A127780 11, 22, 33, 44, 55, 66; %e A127780 ... %Y A127780 Cf. A127775, A002260, A002414. %K A127780 nonn,tabl %O A127780 1,2 %A A127780 _Gary W. Adamson_, Jan 28 2007