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 A000308 #19 Feb 01 2022 00:52:27 %S A000308 1,2,3,6,36,648,139968,3265173504,296148833645101056, %T A000308 135345882205792807436868315512832, %U A000308 130876399105969522361889021452224949874232743897657526714368 %N A000308 a(n) = a(n-1)*a(n-2)*a(n-3) with a(1)=1, a(2)=2 and a(3)=3. %H A000308 John Cerkan, <a href="/A000308/b000308.txt">Table of n, a(n) for n = 1..15</a> %F A000308 a(n) = 2^A001590(n-1)*3^A000073(n-1). - _Henry Bottomley_, Jul 16 2001 %e A000308 a(6)=36*6*3=648. %p A000308 A000308 := proc(n) option remember; if n <=3 then n else A000308(n-1)*A000308(n-2)*A000308(n-3); fi; end; %Y A000308 Cf. A000304, A000336, A063401. %K A000308 nonn %O A000308 1,2 %A A000308 _N. J. A. Sloane_