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 A033646 #5 Mar 30 2012 18:35:33 %S A033646 1,1,2,6,24,120,720,5040,40320,5040,45360,95760,332640,1426320, %T A033646 7464240,46211760,330946560,2693784240,661893120,6049461600, %U A033646 13422709440,52367051520,236313624960,1286302227840,8190440616960,59905688774400 %N A033646 Base 9 digital convolution sequence. %e A033646 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 A033646 base,nonn %O A033646 0,3 %A A033646 _David W. Wilson_