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A077821
Expansion of (1-x)^(-1)/(1-3*x-3*x^2-3*x^3).
0
1, 4, 16, 64, 253, 1000, 3952, 15616, 61705, 243820, 963424, 3806848, 15042277, 59437648, 234860320, 928020736, 3666956113, 14489511508, 57253465072, 226229798080, 893918323981, 3532204761400, 13957058650384, 55149545207296, 217916425857241, 861069089144764
OFFSET
0,2
FORMULA
a(0)=1, a(1)=4, a(2)=16, a(3)=64, a(n)=4*a(n-1)-3*a(n-4) [From Harvey P. Dale, May 10 2011]
MATHEMATICA
LinearRecurrence[{4, 0, 0, -3}, {1, 4, 16, 64}, 40] (* or *) CoefficientList[ Series[(1-x)^(-1)/(1-3x-3x^2-3x^3), {x, 0, 40}], x] (* Harvey P. Dale, May 10 2011 *)
CROSSREFS
Sequence in context: A188714 A005755 A269651 * A215877 A206450 A294452
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved