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Search: id:A113312
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A113312 Expansion of (1+x)^2/(1-2x^2+x^3). +0
2
1, 2, 3, 3, 4, 3, 5, 2, 7, -1, 12, -9, 25, -30, 59, -85, 148, -229, 381, -606, 991, -1593, 2588, -4177, 6769, -10942, 17715, -28653, 46372, -75021, 121397, -196414, 317815, -514225, 832044, -1346265, 2178313, -3524574, 5702891, -9227461, 14930356, -24157813, 39088173, -63245982, 102334159 (list; graph; listen)
OFFSET

0,2

COMMENT

Diagonal sums of A113310.

FORMULA

a(n)=2a(n-2)-a(n-3); a(n)=sum{k=0..floor(n/2), sum{i=0..n-2k, (-1)^i*C(i+k-2, i)}}.

CROSSREFS

Sequence in context: A049108 A086925 A088858 this_sequence A053475 A140605 A049878

Adjacent sequences: A113309 A113310 A113311 this_sequence A113313 A113314 A113315

KEYWORD

easy,sign

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Oct 25 2005

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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