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A210677
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a(n)=a(n-1)+a(n-2)+n+1, a(0)=a(1)=1.
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2
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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
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..38.
Index to sequences with linear recurrences with constant coefficients, signature (3,-2,-1,1).
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FORMULA
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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]
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CROSSREFS
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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 A020714 A146523
Adjacent sequences: A210674 A210675 A210676 * A210678 A210679 A210680
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KEYWORD
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nonn,easy
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AUTHOR
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Alex Ratushnyak, May 09 2012
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STATUS
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approved
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