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A098588 a(n)=2a(n-1)+a(n-5). 0
1, 2, 4, 8, 16, 33, 68, 140, 288, 592, 1217, 2502, 5144, 10576, 21744, 44705, 91912, 188968, 388512, 798768, 1642241, 3376394, 6941756, 14272024, 29342816, 60327873, 124032140, 255006036, 524284096, 1077911008, 2216149889 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

G.f.: 1/(1-2x-x^5); a(n)=sum{k=0..floor(n/4), sum{i=0..n, binomial(n-4k, i)binomial(i, k)}}.

CROSSREFS

Cf. A008998, A008999.

Sequence in context: A036373 A119610 A121485 * A126683 A005821 A177794

Adjacent sequences:  A098585 A098586 A098587 * A098589 A098590 A098591

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Sep 16 2004

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Last modified February 14 19:37 EST 2012. Contains 205663 sequences.