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 A004527 #9 Oct 26 2023 00:34:00 %S A004527 1,1,2,4,12,48,192,960,5760,34560,241920,1935360,15482880,139345920, %T A004527 1393459200,13934592000,153280512000,1839366144000,22072393728000, %U A004527 286941118464000,4017175658496000,56240459218944000 %N A004527 Ratios of successive terms are 1,2,2,3,4,4,5,6,6,... %H A004527 Harvey P. Dale, <a href="/A004527/b004527.txt">Table of n, a(n) for n = 0..480</a> %t A004527 FoldList[Times,1,Flatten[Append[#,Last[#]]&/@Partition[Range[20],2]]] (* _Harvey P. Dale_, Oct 15 2011 *) %K A004527 nonn %O A004527 0,3 %A A004527 _N. J. A. Sloane_