A008380 - OEIS

%I #6 Mar 30 2012 16:45:19

%S 6,50,1176,54792,4251456,495480960,80990184960,17683570598400,

%T 4972664013004800,1750589607352320000,754268505333719040000,

%U 390464536066453094400000,239146855253471119933440000

%N 4*(2n-1)!*H(2n), where H(n) = Sum 1/i are harmonic numbers.

%K nonn

%O 1,1

%A _N. J. A. Sloane_.