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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). 4

%I

%S 1,2,2,3,4,3,4,24,24,4,5,288,2304,288,5,6,5760,15925248,15925248,5760,

%T 6,7,172800,26418075402240,584325558976905216,26418075402240,172800,7,

%U 8,7257600,26294650153960734720000,245834178389044369818454697074564792320

%N 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 Vincenzo Librandi, <a href="/A047675/b047675.txt">Table of n, a(n) for n = 1..70</a>

%p 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 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-Fran├žois Alcover_, Oct 08 2013 *)

%Y Main diagonal is A047676. Rows give A047677, A047678.

%K nonn,tabl,nice,easy

%O 1,2

%A _N. J. A. Sloane_

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Last modified April 10 08:09 EDT 2021. Contains 342845 sequences. (Running on oeis4.)