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 A033642 #5 Mar 30 2012 18:35:33 %S A033642 1,1,2,6,24,6,30,66,228,978,456,2412,5736,22032,99600,66096,364896, %T A033642 928080,3878928,18299952,15515712,88715520,239493888,1073343744, %U A033642 5251350528,239493888,1312837632,7877025792,23870571264,96795122688 %N A033642 Base 5 digital convolution sequence. %e A033642 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 A033642 base,nonn %O A033642 0,3 %A A033642 _David W. Wilson_