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A099493 Expansion of (1+x^2)^2/(1+x^2-2x^3+x^4+x^6). 1
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; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

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)).

LINKS

Table of n, a(n) for n=0..48.

FORMULA

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}}.

CROSSREFS

Sequence in context: A221542 A221463 A135488 * A088523 A222211 A145460

Adjacent sequences:  A099490 A099491 A099492 * A099494 A099495 A099496

KEYWORD

easy,sign

AUTHOR

Paul Barry, Oct 19 2004

STATUS

approved

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Last modified October 2 05:40 EDT 2014. Contains 247537 sequences.