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Search: id:A076149
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| A076149 |
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Expansion of x^2(3+2x)/(1-x-5x^2-3x^3). |
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+0
1
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| 0, 3, 5, 20, 54, 169, 499, 1506, 4508, 13535, 40593, 121792, 365362, 1096101, 3288287, 9864878, 29594616, 88783867, 266351581, 799054764, 2397164270, 7191492833, 21574478475, 64723435450, 194170306324, 582510918999
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Let b(1)=x, b(2)=y, k*b(k)=(2k-1)*b(k-1) + 3(k+1)*b(k-2); then b(n)=c(n)*x+a(n)/3*y.
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FORMULA
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a(1)=0; a(n+1) = 3*a(n)-(-1)^n*(n+2); a(n)=floor((11/48)*3^n+(-1)^n*n/4+1/2)
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PROGRAM
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(PARI) a(n)=if(n<0, 0, polcoeff(x^2*(3+2*x)/(1-x-5*x^2-3*x^3)+x*O(x^n), n))
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CROSSREFS
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Sequence in context: A055452 A077458 A062577 this_sequence A133102 A066902 A007363
Adjacent sequences: A076146 A076147 A076148 this_sequence A076150 A076151 A076152
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 02 2002
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