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Search: id:A099493
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| A099493 |
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Expansion of (1+x^2)^2/(1+x^2-2x^3+x^4+x^6). |
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+0
2
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| 1, 0, 1, 2, -1, 0, 3, -4, -3, 8, -7, -10, 23, -8, -33, 56, 1, -104, 121, 58, -297, 232, 291, -780, 349, 1072, -1903, 174, 3407, -4272, -1505, 9840, -8543, -8752, 26321, -13902, -33777, 65456, -11805, -110356, 150173, 35192, -325303, 310054, 257319, -885496, 537919, 1054888, -2240927
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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A Chebyshev transform of A052907, which has g.f. 1/(1-2x^2-2x^3). The image of G(x) under the Chebyshev transform is (1/(1+x^2))G(x/(1+x^2)).
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FORMULA
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a(n)=-a(n-2)+2a(n-3)-a(n-4)-a(n-6); a(n)=sum{k=0..floor(n/2), C(n-k, k)(-1)^k*sum{j=0.., floor(n-2k/2), C(j, n-2k-2j)2^j}}.
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CROSSREFS
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Sequence in context: A106378 A094301 A135488 this_sequence A088523 A145460 A035543
Adjacent sequences: A099490 A099491 A099492 this_sequence A099494 A099495 A099496
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Oct 19 2004
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