A124996
a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1/x^k)^4.
Original entry on oeis.org
1, 6, 44, 426, 4658, 55260, 689508, 8914872, 118374410, 1604658420, 22115171280, 308940507202, 4364729023812, 62256518307724, 895294865045296, 12966655239260890, 188967013096930258, 2769003814616561636, 40773380119956434784, 603008173331642200144
Offset: 0
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.
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a(n) = polcoef(prod(k=1, n, (x^k + 1/x^k)^4), 0); \\ Michel Marcus, Jan 07 2021
A350282
a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1/x^k)^n.
Original entry on oeis.org
1, 0, 4, 62, 4658, 0, 2319512420, 14225426190522, 361926393013029354, 0, 16231015449888734994721650504, 28330316118212024049511095643949434, 200866780133770636272812495083578779133456, 0
Offset: 0
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a(n) = polcoef(prod(k=1, n, x^k+1/x^k)^n, 0);
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a(n) = polcoef(prod(k=1, n, 1+x^(2*k))^n, n^2*(n+1)/2);
A369372
a(n) is the constant term in expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^3.
Original entry on oeis.org
1, 7, 85, 1437, 26707, 534513, 11255951, 245612031, 5503639327, 125900330437, 2928092906281, 69026845135479, 1645689594867257, 39611576627651927, 961279033420170871, 23494000801494204647, 577777092945262623161, 14287061769367391787065, 355010279665452190629001
Offset: 0
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Table[Coefficient[Product[(x^k + 1 + 1/x^k)^3, {k, 1, n}], x, 0], {n, 0, 18}]
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a(n) = polcoef(prod(k=1, n, (x^k + 1 + 1/x^k)^3), 0); \\ Michel Marcus, Jan 22 2024
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