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A171507 a(n) = (5*2^(n+1)-9-(-1)^n)/6-2*n. 2
0, 0, 1, 6, 17, 42, 93, 198, 409, 834, 1685, 3390, 6801, 13626, 27277, 54582, 109193, 218418, 436869, 873774, 1747585, 3495210, 6990461, 13980966, 27961977, 55924002, 111848053, 223696158, 447392369, 894784794, 1789569645, 3579139350, 7158278761, 14316557586 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

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

FORMULA

a(n) = 3*a(n-1)-a(n-2)-3*a(n-3)+2*a(n-4). G.f.: x^2*(1+3*x)/((1+x)*(1-2*x)*(1-x)^2).

a(n) = A084640(n) - A042948(n).

a(n+1)-2*a(n) = A042948(n+1).

First differences: a(n+1)-a(n) = A084640(n).

Last digits: a(n) == a(n+10) (mod 10), n>=1.

MAPLE

A171507:=n->(5*2^(n+1)-9-(-1)^n)/6 -2*n: seq(A171507(n), n=0..50); # Wesley Ivan Hurt, May 03 2017

PROG

(MAGMA) [(5*2^(n+1)-9-(-1)^n)/6 -2*n: n in [0..40]]; // Vincenzo Librandi, Aug 05 2011

CROSSREFS

Cf. A042948, A084640.

Sequence in context: A220407 A013319 A047861 * A099858 A232567 A062020

Adjacent sequences:  A171504 A171505 A171506 * A171508 A171509 A171510

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Dec 10 2009

EXTENSIONS

Edited and extended by R. J. Mathar, Dec 15 2009

STATUS

approved

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Last modified October 16 06:02 EDT 2019. Contains 328046 sequences. (Running on oeis4.)