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 A033644 #5 Mar 30 2012 18:35:33 %S A033644 1,1,2,6,24,120,720,120,840,1800,6240,26760,140040,867000,280080, %T A033644 2014080,4588320,17793120,80349120,437331840,2784689280,1311995520, %U A033644 9666063360,23268113280,98802529920,465014459520,2621479887360 %N A033644 Base 7 digital convolution sequence. %e A033644 Suppose base = 3 and a(0)..a(13) are 1 1 2 1 3 7 6 20 52 6 26 104 32 162. In base 3, 14 = 112, so we convolve the last three terms with 1, 1, 2 to obtain 104*1+32*1+162*2 = 460. %K A033644 base,nonn %O A033644 0,3 %A A033644 _David W. Wilson_