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Search: id:A155116
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| A155116 |
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a(n)=3*a(n-1)+3*a(n-2), n>2 ; a(0)=1, a(1)=2, a(2)=8 . |
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+0
1
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| 1, 2, 8, 30, 114, 432, 1638, 6210, 23544, 89262, 338418, 1283040, 4864374, 18442242, 69919848, 265086270, 1005018354, 3810313872, 14445996678, 54768931650, 207644784984, 787241149902, 2984657804658, 11315696863680, 42901064005014
(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)/(1-3*x-3*x^2). a(n)=2*A125145(n-1), n>=1 .
a(n)=(1/3)*sqrt(3)*{[1+sqrt(3)]^(n-1)-[1-sqrt(3)]^(n-1)}+(1/2)*{[1+sqrt(3)]^(n-1)+[1-sqrt(3)]^(n-1)}+(1/2)*[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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Sequence in context: A052530 A162551 A073663 this_sequence A133915 A150759 A150760
Adjacent sequences: A155113 A155114 A155115 this_sequence A155117 A155118 A155119
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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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