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A097116 Expansion of (1-x)/((1-x)^2-3x^3). 1
1, 1, 1, 4, 10, 19, 40, 91, 199, 427, 928, 2026, 4405, 9568, 20809, 45265, 98425, 214012, 465394, 1012051, 2200744, 4785619, 10406647, 22629907, 49210024, 107010082, 232699861, 506019712, 1100369809, 2392819489, 5203328305 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..30.

FORMULA

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

CROSSREFS

Sequence in context: A057318 A008118 A301160 * A155380 A155445 A133952

Adjacent sequences:  A097113 A097114 A097115 * A097117 A097118 A097119

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jul 25 2004

STATUS

approved

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Last modified January 20 14:26 EST 2020. Contains 331094 sequences. (Running on oeis4.)