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%I #20 Jan 07 2021 10:32:16
%S 1,6,44,426,4658,55260,689508,8914872,118374410,1604658420,
%T 22115171280,308940507202,4364729023812,62256518307724,
%U 895294865045296,12966655239260890,188967013096930258,2769003814616561636,40773380119956434784,603008173331642200144
%N a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1/x^k)^4.
%H Ray Chandler, <a href="/A124996/b124996.txt">Table of n, a(n) for n = 0..834</a> (terms < 10^1000)
%F a(n) ~ sqrt(3) * 16^n / (sqrt(2*Pi) * n^(3/2)). - _Vaclav Kotesovec_, Jan 07 2021
%o (PARI) a(n) = polcoef(prod(k=1, n, (x^k + 1/x^k)^4), 0); \\ _Michel Marcus_, Jan 07 2021
%Y For constant term in expansion of Product_{k=1..n} (x^k + 1/x^k)^q for other values of q see A063865, A047653, A124995.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Jul 12 2008