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Search: id:A075419
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| A075419 |
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a(n)=Sum((-1)^(i+Floor(n/2))C(2i+e),(i=0,..,Floor(n/2))), where C(n) are reflected tribonacci numbers (A073145). |
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+0
2
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| 3, -1, -4, 6, -1, -7, 12, -8, -9, 31, -32, -10, 75, -95, 8, 160, -261, 111, 308, -682, 487, 505, -1676, 1656, 527, -3857, 4984, -602, -8237, 13825, -6192, -15872, 35891, -26209, -25556, 87654, -88305, -24903, 200860, -264264, 38503, 426623, -729392, 341270, 814747, -1885407, 1411928, 1288224
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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a(n) is the convolution of C(n) with the sequence (1,0,-1,0,1,0,-1,0,....) A056594.
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FORMULA
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a(n)=-a(n-1)-2a(n-2)-a(n-4)+a(n-5), a(0)=3, a(1)=-1, a(2)=-4, a(3)=6, a(4)=-1. Ogf (3 + 2x + x^2)/(1 + x + 2x^2 + x^4 - x^5).
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MATHEMATICA
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CoefficientList[Series[(3 + 2x + x^2)/(1 + x + 2x^2 + x^4 - x^5), {x, 0, 50}], x]
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CROSSREFS
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Cf. A073145.
Sequence in context: A086271 A080851 A108285 this_sequence A060922 A135611 A011089
Adjacent sequences: A075416 A075417 A075418 this_sequence A075420 A075421 A075422
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KEYWORD
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easy,sign
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AUTHOR
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Mario Catalani (mario.catalani(AT)unito.it), Sep 17 2002
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