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 A047675 #14 Jun 24 2017 13:45:16
%S A047675 1,2,2,3,4,3,4,24,24,4,5,288,2304,288,5,6,5760,15925248,15925248,5760,
%T A047675 6,7,172800,26418075402240,584325558976905216,26418075402240,172800,7,
%U A047675 8,7257600,26294650153960734720000,245834178389044369818454697074564792320
%N A047675 Square array a(n,k) read by antidiagonals: a(n,1)=n, a(1,k)=k, a(n,k) = a(n-1,k-1)*a(n-1,k)*a(n,k-1).
%H A047675 Vincenzo Librandi, <a href="/A047675/b047675.txt">Table of n, a(n) for n = 1..70</a>
%p A047675 A047675 := proc(n,k) option remember; if n = 1 then k; elif k = 1 then n; else A047675(n-1,k-1)*A047675(n,k-1)*A047675(n-1,k); fi; end;
%t A047675 a[n_, 1] := n; a[1, k_] := k; a[n_, k_] := a[n, k] = a[n-1, k-1]*a[n-1, k]*a[n, k-1]; Table[a[n-k+1, k], {n, 1, 8}, {k, 1, n}] // Flatten (* _Jean-François Alcover_, Oct 08 2013 *)
%Y A047675 Main diagonal is A047676. Rows give A047677, A047678.
%K A047675 nonn,tabl,nice,easy
%O A047675 1,2
%A A047675 _N. J. A. Sloane_