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A369729
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Number of solutions to +- 1 +- 3 +- 5 +- 7 +- ... +- (4*n-3) = 1.
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0
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0, 1, 1, 2, 5, 13, 38, 118, 380, 1262, 4277, 14745, 51541, 182182, 650095, 2338706, 8472697, 30884150, 113189168, 416839177, 1541726967, 5724470097, 21330062502, 79733319862, 298922247363, 1123678419818, 4234465089737, 15993581636893, 60535561889465
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = [x^1] Product_{k=1..2*n-1} (x^(2*k-1) + 1/x^(2*k-1)).
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MATHEMATICA
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Table[Coefficient[Product[(x^(2 k - 1) + 1/x^(2 k - 1)), {k, 1, 2 n - 1}], x, 1], {n, 0, 27}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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