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A052938
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Expansion of ( 1+2*x-2*x^2 ) / ( (1+x)*(x-1)^2 ).
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7
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1, 3, 2, 4, 3, 5, 4, 6, 5, 7, 6, 8, 7, 9, 8, 10, 9, 11, 10, 12, 11, 13, 12, 14, 13, 15, 14, 16, 15, 17, 16, 18, 17, 19, 18, 20, 19, 21, 20, 22, 21, 23, 22, 24, 23, 25, 24, 26, 25, 27, 26, 28, 27, 29, 28, 30, 29, 31, 30, 32, 31, 33, 32, 34, 33, 35, 34, 36, 35, 37, 36, 38, 37, 39
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..73.
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 929
Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).
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FORMULA
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G.f.: -(-2*x+2*x^2-1)/(-1+x)/(-1+x^2)
Recurrence: {a(0)=1, a(2)=2, a(1)=3, a(n)+a(n+1)-n-4 =0}
3/4*(-1)^(1-n)+1/2*n+7/4
A112034(n) = 3*2^a(n); a(n) = A109613(n+2) - A084964(n). - Reinhard Zumkeller, Aug 27 2005
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MAPLE
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spec := [S, {S=Prod(Union(Sequence(Z), Z, Z), Sequence(Prod(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
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Cf. A028242 (same sequence with 1,0,2 prefix). [From Rick L. Shepherd, Jul 16 2009]
Sequence in context: A134559 A007456 A119707 * A140114 A025532 A195459
Adjacent sequences: A052935 A052936 A052937 * A052939 A052940 A052941
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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More terms from James A. Sellers, Jun 06 2000
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STATUS
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approved
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