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Search: id:A104510
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| A104510 |
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G.f.: Product((1-2*(-x)^i)/(1-(-x)^i)^2,i=1..infinity). |
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+0
2
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| 0, -1, 2, -4, 4, -7, 4, -5, 0, 5, -18, 23, -46, 65, -82, 108, -132, 152, -164, 168, -144, 132, -48, -39, 212, -365, 658, -947, 1382, -1800, 2394, -2947, 3644, -4289, 5102, -5687, 6392, -6820, 7112, -7139, 6776, -5836, 4338, -2036, -1342, 5585, -11392, 18513, -27456, 37876, -51072, 65488, -82982, 101898
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(n) = Sum (k(1)-1)*(k(2)-1)*...*(k(n)-1), where the sum is taken over all (k(1), k(2), ..., k(n)) such that k(1)+2*k(2)+...+n*k(n) = n, k(i)>=0, i=1...n.
G.f.: Product((1-(-x)^i)^A052823(i), i=1..infinity). - James A. Sellers (sellersj(AT)math.psu.edu), Apr 22 2005
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MAPLE
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gf:=product((1-2*(-x)^i)/(1-(-x)^i)^2, i=1..100): s:=series(gf, x, 100): for n from 1 to 99 do printf(`%d, `, coeff(s, x, n)) od: (Sellers)
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CROSSREFS
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Cf. A000712, A077285.
Cf. A104575.
Adjacent sequences: A104507 A104508 A104509 this_sequence A104511 A104512 A104513
Sequence in context: A002086 A039830 A096612 this_sequence A082515 A062855 A103622
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KEYWORD
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easy,sign
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 19 2005
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 22 2005
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