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 A013621 #7 Jul 08 2025 02:48:42 %S A013621 1,2,5,4,20,25,8,60,150,125,16,160,600,1000,625,32,400,2000,5000,6250, %T A013621 3125,64,960,6000,20000,37500,37500,15625,128,2240,16800,70000,175000, %U A013621 262500,218750,78125,256,5120,44800,224000,700000,1400000 %N A013621 Triangle of coefficients in expansion of (2+5x)^n. %F A013621 G.f.: 1 / [1 - x(2+5y)]. %K A013621 tabl,nonn,easy %O A013621 0,2 %A A013621 _N. J. A. Sloane_