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%I #19 Nov 08 2014 06:58:05
%S 1,1,5,150,6932,965380,143299890,51176650000,16737737386944,
%T 11806879466638656,7023172771916784000,8447153882019234307200,
%U 8134080139379917205277696,15176253254155788712392633600,21875035292051870323313614135440,59270306784445546617788929301760000
%N A232773(n) / A006882(n): Permanent of the n X n matrix with elements [1,2,...,n^2], divided by n!!.
%C Limit n->infinity a(n)^(1/n)/n^(5/2) = exp(-3/2). - _Vaclav Kotesovec_, Nov 08 2014
%H Alois P. Heinz, <a href="/A232788/b232788.txt">Table of n, a(n) for n = 0..100</a>
%p with(combinat):
%p a:= n-> (-1)^n *add(n^k *stirling1(n, n-k)*stirling1(n+1, k+1)
%p *(n-k)!* k!, k=0..n)/doublefactorial(n):
%p seq(a(n), n=0..20); # _Alois P. Heinz_, Dec 02 2013
%t Flatten[{1,Table[(-1)^n*Sum[n^k*StirlingS1[n,n-k]*StirlingS1[n+1,k+1]*(n-k)!*k!,{k,0,n}]/n!!,{n,1,20}]}] (* _Vaclav Kotesovec_, Nov 08 2014 *)
%o (PARI) n->(-1)^n*sum(k=0,n,n^k*stirling(n,n-k)*stirling(n+1,k+1)*(n-k)!*k!)/A006882(n)
%Y Cf. A232773, A006882.
%K nonn
%O 0,3
%A _M. F. Hasler_, Nov 30 2013
%E a(0)=1 inserted by _Alois P. Heinz_, Dec 02 2013
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