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 A117826 #3 Mar 30 2012 17:31:18
%S A117826 1,2,3,4,2,4,6,8,6,12,18,24,24,48,72,96,120,240,360,480,720,1440,2160,
%T A117826 2880,5040,10080,15120,20160,40320,80640,120960,161280,362880,725760,
%U A117826 1088640,1451520,3628800,7257600,10886400,14515200,39916800,79833600
%N A117826 First four terms of the sequence are doubled, then those numbers are tripled and then those numbers are quadrupled, etc.
%F A117826 a(4n-3) = A000142(n). a(4n-2)=2*A000142(n)=A052849(n), a(4n-1)=3*A000142(n)=A052560(n), a(4n)=4*A000142(n)=2*A052849(n)=A052578(n).
%t A117826 Table[n!{1, 2, 3, 4}, {n, 11}] // Flatten
%Y A117826 Cf. A000142, A115425.
%K A117826 nonn
%O A117826 1,2
%A A117826 _Robert G. Wilson v_, Apr 25 2006