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 A368839 #8 Jan 07 2024 10:33:58
%S A368839 1,7,169,10141,1216921,255553411,85865946097,43276436832889,
%T A368839 31159034519680081,30847444174483280191,40718626310317929852121,
%U A368839 69873162748505567626239637,152602987442736159695707367209,416606155718669715969281112480571
%N A368839 a(n) = n! * (n+1)! * (n+2)! * Sum_{k=0..n} 1/(k! * (k+1)! * (k+2)!).
%F A368839 a(n) = n*(n+1)*(n+2)*a(n-1) + 1.
%o A368839 (PARI) a(n) = n!*(n+1)!*(n+2)!*sum(k=0, n, 1/(k!*(k+1)!*(k+2)!));
%Y A368839 Cf. A000522, A228229.
%Y A368839 Cf. A368840.
%K A368839 nonn,easy
%O A368839 0,2
%A A368839 _Seiichi Manyama_, Jan 07 2024