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Search: id:A133594
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| A133594 |
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a(n)=3*a(n-1)+12*a(n-2) for n>=3, a(0)=1, a(1)=3, a(2)=18 . |
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+0
2
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| 1, 3, 18, 90, 486, 2538, 13446, 70794, 373734, 1970730, 10396998, 54839754, 289283238, 1525926762, 8049179142, 42458658570, 223966125414, 1181402279082, 6231800342214, 32872228375626, 173398289233446, 914661608207850
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OFFSET
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0,2
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FORMULA
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G.f.: (1-3*x^2)/(1-3*x-12*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*3^k .
a(n)=(3/2)*[(3/2)-(1/2)*sqrt(57)]^(n-1)+(3/2)*[(3/2)+(1/2)*sqrt(57)]^(n-1)+(9/38)*sqrt(57)*[(3/2)+(1/2) *sqrt(57)]^(n-1)-(9/38)*sqrt(57)*[(3/2)-(1/2)*sqrt(57)]^(n-1),100)+(1/4)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 18 2008]
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CROSSREFS
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Sequence in context: A006568 A147518 A088336 this_sequence A092691 A064671 A058409
Adjacent sequences: A133591 A133592 A133593 this_sequence A133595 A133596 A133597
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KEYWORD
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easy,nonn
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 31 2007
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