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 A014231 #11 Jul 08 2025 02:55:47 %S A014231 1,5,70,1470,38808,1189188,40489020,1491345570,58388438680, %T A014231 2400295633736,102692368441936,4542162450316400,206643434552856000, %U A014231 9631060074695610000,458381806260954003000,22220282755463598704250,1094733022441519300455000,54717445279576990999935000 %N A014231 (Product of 3 successive Catalan numbers)/2. %H A014231 Harvey P. Dale, <a href="/A014231/b014231.txt">Table of n, a(n) for n = 0..560</a> %F A014231 a(n) = A014228(n)/2. %p A014231 a:= proc(n) option remember; `if`(n=0, 1, %p A014231 8*(2*n-1)*(2*n+1)*(2*n+3)*a(n-1)/((n+1)*(n+2)*(n+3))) %p A014231 end: %p A014231 seq(a(n), n=0..20); # _Alois P. Heinz_, Oct 20 2013 %t A014231 Times@@@Partition[CatalanNumber[Range[0,20]],3,1]/2 (* _Harvey P. Dale_, Apr 10 2013 *) %Y A014231 Cf. A000108. %K A014231 nonn %O A014231 0,2 %A A014231 _N. J. A. Sloane_