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A117080 a(n) = 2a(n-1)+a(n-3)+1 with a(1)=1, a(2)=3, a(3)=8. 0
1, 3, 8, 18, 40, 89, 197, 435, 960, 2118, 4672, 10305, 22729, 50131, 110568, 243866, 537864, 1186297, 2616461, 5770787, 12727872, 28072206, 61915200, 136558273, 301188753, 664292707, 1465143688, 3231476130, 7127244968, 15719633625, 34670743381, 76468731731 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..32.

Index entries for linear recurrences with constant coefficients, signature (3, -2, 1, -1).

FORMULA

a(n)=3*a(n-1)-2*a(n-2)+a(n-3)-a(n-4). G.f.: x*(-1-x^2+x^3)/((1-x)*(x^3+2*x-1)). [From R. J. Mathar, May 25 2009]

CROSSREFS

Sequence in context: A036384 A294591 A080692 * A240135 A066425 A026679

Adjacent sequences:  A117077 A117078 A117079 * A117081 A117082 A117083

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, following a suggestion of Franklin T. Adams-Watters, Apr 20 2006

STATUS

approved

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Last modified April 16 17:01 EDT 2021. Contains 343050 sequences. (Running on oeis4.)