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%I #4 Mar 30 2012 16:48:44
%S 1,8,160,6144,399360,40058880,5771427840,1131282432000,
%T 289610945003520,93834041307955200,37533620328254668800,
%U 18166272406298453606400,10463772914064222584832000,7073510490325302759338803200,5545632224438439107673194496000
%N 4^n*n!^2*Sum_{k=0..n} 1/k!.
%D R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.64(d).
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Jan 23 2000
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