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Search: id:A091596
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| A091596 |
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Expansion of x(1-2x^2)/(1-x-2x^2)^2. |
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+0
2
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| 0, 1, 2, 5, 12, 27, 62, 137, 304, 663, 1442, 3109, 6676, 14259, 30342, 64321, 135928, 286415, 601962, 1262173, 2640860, 5514731, 11495502, 23923065, 49710272, 103148807, 213754162, 442421397, 914668964, 1888990243, 3897285142
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Second column of A091595.
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FORMULA
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a(n) := sum{k=0..floor((n-1)/2), binomial(n-k-1, k)2^k }; a(n)=2a(n-1)+3a(n-2)-4a(n-3)-4a(n-4).
a(n)=(1/9)*(-1)^n*n-(8/27)*(-1)^n+(8/27)*2^n+(1/9)*2^n*n, with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jun 10 2008
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CROSSREFS
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Sequence in context: A116712 A000102 A086589 this_sequence A077863 A018009 A128096
Adjacent sequences: A091593 A091594 A091595 this_sequence A091597 A091598 A091599
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 23 2004
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