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 A137681 #7 Sep 19 2024 07:19:57 %S A137681 1,2,4,10,23,56,132,316,752,1793,4272,10183,24266,57833,137828,328475, %T A137681 782827,1865651,4446255,10596406,25253567,60184809,143433647, %U A137681 341833954,814665553,1941527332,4627086990,11027366781,26280642313,62632555360,149267165702 %N A137681 Row sums of triangle A137680. %C A137681 Partial sums of A137681 prefaced with a 1 = left border of triangle A137680: (1, 1, 3, 7, 17, 40, 96, 228, ...) = A137682. A variation of A137681 = column 2 of triangle A137680: (1, 0, 2, 4, 10, 23, 56, 132, 316, ...). %e A137681 a(4) = 10 = sum of row 4 terms of triangle A137680: (7 + 2 + 0 + 1). %Y A137681 Cf. A137680, A137682. %K A137681 nonn %O A137681 1,2 %A A137681 _Gary W. Adamson_, Feb 05 2008