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A210677 a(n)=a(n-1)+a(n-2)+n+1, a(0)=a(1)=1. 2
1, 1, 5, 10, 20, 36, 63, 107, 179, 296, 486, 794, 1293, 2101, 3409, 5526, 8952, 14496, 23467, 37983, 61471, 99476, 160970, 260470, 421465, 681961, 1103453, 1785442, 2888924, 4674396, 7563351, 12237779, 19801163, 32038976, 51840174, 83879186, 135719397, 219598621, 355318057 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..38.

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.: (1-2*x+4*x^2-2*x^3)/((1-x)^2*(1-x-x^2)). [Colin Barker, Jun 30 2012]

MATHEMATICA

LinearRecurrence[{3, -2, -1, 1}, {1, 1, 5, 10}, 39] (* Jean-Fran├žois Alcover, Oct 05 2017 *)

CROSSREFS

Cf. A081659: a(n)=a(n-1)+a(n-2)+n-5, a(0)=a(1)=1 (except first 2 terms and sign).

Cf. A001924: a(n)=a(n-1)+a(n-2)+n-4, a(0)=a(1)=1 (except first 4 terms).

Cf. A000126: a(n)=a(n-1)+a(n-2)+n-2, a(0)=a(1)=1 (except first term).

Cf. A066982: a(n)=a(n-1)+a(n-2)+n-1, a(0)=a(1)=1.

Cf. A030119: a(n)=a(n-1)+a(n-2)+n,   a(0)=a(1)=1.

Cf. A210678: a(n)=a(n-1)+a(n-2)+n+2, a(0)=a(1)=1.

Sequence in context: A026357 A117518 A107486 * A193839 A323831 A020714

Adjacent sequences:  A210674 A210675 A210676 * A210678 A210679 A210680

KEYWORD

nonn,easy

AUTHOR

Alex Ratushnyak, May 09 2012

STATUS

approved

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Last modified October 23 13:38 EDT 2019. Contains 328345 sequences. (Running on oeis4.)