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Search: id:A155119
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| A155119 |
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a(n)=5*a(n-1)+5*a(n-2), n>2 ; a(0)=1, a(1)=4, a(2)=24 . |
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+0
1
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| 1, 4, 24, 140, 820, 4800, 28100, 164500, 963000, 5637500, 33002500, 193200000, 1131012500, 6621062500, 38760375000, 226907187500, 1328337812500, 7776225000000, 45522814062500, 266495195312500, 1540090046875000
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: (1-x-x^2)/(1-5*x-5*x^2) .
a(n)=(14/15)*sqrt(5)*{[(5/2)+(3/2)*sqrt(5)]^(n-1)-[(5/2)-(3/2)*sqrt(5)]^(n-1)}+2*{[(5/2)+(3/2)*sqrt(5)]^(n-1)+[(5/2)-(3/2)*sqrt(5)]^(n-1)}+(1/5)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Jan 26 2009]
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CROSSREFS
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Adjacent sequences: A155116 A155117 A155118 this_sequence A155120 A155121 A155122
Sequence in context: A153337 A122690 A005319 this_sequence A114169 A121102 A067411
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KEYWORD
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nonn
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 20 2009
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