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A341251
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Expansion of (-1 + Product_{k>=1} 1 / (1 + (-x)^k))^9.
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10
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1, 0, 9, 9, 45, 81, 201, 414, 828, 1650, 3060, 5697, 10131, 17829, 30564, 51543, 85482, 139455, 224527, 356436, 559341, 867405, 1331208, 2022525, 3044331, 4542174, 6720705, 9866794, 14377941, 20804994, 29903823, 42709860, 60631011, 85575855, 120118500, 167716548
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OFFSET
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9,3
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LINKS
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FORMULA
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G.f.: (-1 + Product_{k>=1} (1 + x^(2*k - 1)))^9.
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MAPLE
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g:= proc(n) option remember; `if`(n=0, 1, add(add([0, d, -d, d]
[1+irem(d, 4)], d=numtheory[divisors](j))*g(n-j), j=1..n)/n)
end:
b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, g(n)),
(q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
end:
a:= n-> b(n, 9):
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MATHEMATICA
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nmax = 44; CoefficientList[Series[(-1 + Product[1/(1 + (-x)^k), {k, 1, nmax}])^9, {x, 0, nmax}], x] // Drop[#, 9] &
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CROSSREFS
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Cf. A000700, A001487, A022604, A327387, A338463, A341228, A341241, A341243, A341244, A341245, A341246, A341247.
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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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