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A097118 Expansion of (1+x)/(1-x)^2-5x^3). 0
1, 1, 1, 6, 16, 31, 76, 201, 481, 1141, 2806, 6876, 16651, 40456, 98641, 240081, 583801, 1420726, 3458056, 8414391, 20474356, 49824601, 121246801, 295040781, 717957766, 1747108756, 4251463651, 10345607376, 25175294881, 61262300641 (list; graph; refs; listen; history; internal format)
OFFSET

0,4

FORMULA

G.f. : (1+x)/(1-2x+x^2-5x^3); a(n)=2a(n-1)-a(n-2)+5a(n-3); a(n)=sum{k=0..floor(n/2), binomial(n-k, 2k)5^k }.

CROSSREFS

Sequence in context: A005891 A092286 A108182 * A134465 A036488 A131949

Adjacent sequences:  A097115 A097116 A097117 * A097119 A097120 A097121

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Jul 25 2004

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Last modified February 17 21:13 EST 2012. Contains 206085 sequences.