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A369343
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a(n) is the constant term in expansion of Product_{k=1..n} (x^(2*k-1) + 1 + 1/x^(2*k-1)).
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2
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1, 1, 1, 1, 3, 9, 21, 49, 117, 295, 761, 1993, 5261, 14025, 37699, 102151, 278587, 764145, 2106433, 5832863, 16217191, 45255167, 126708863, 355848715, 1002145705, 2829479797, 8007670701, 22711890561, 64547494347, 183790615881, 524239904367, 1497786769295
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OFFSET
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0,5
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COMMENTS
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All terms are odd.
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LINKS
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FORMULA
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MAPLE
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b:= proc(n, i) option remember; `if`(n>i^2, 0, `if`(i=0, 1,
b(n, i-1)+b(n+2*i-1, i-1)+b(abs(n-2*i+1), i-1)))
end:
a:= n-> b(0, n):
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MATHEMATICA
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Table[Coefficient[Product[x^(2 k - 1) + 1 + 1/x^(2 k - 1), {k, 1, n}], x, 0], {n, 0, 30}]
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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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