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Search: id:A165310
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| A165310 |
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a(0)=1, a(1)=3, a(n)=7*a(n-1)-9*a(n-2) for n>1 . |
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+0
2
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| 1, 3, 12, 57, 291, 1524, 8049, 42627, 225948, 1197993, 6352419, 33684996, 178623201, 947197443, 5022773292, 26634636057, 141237492771, 748950724884, 3971517639249, 21060066950787, 111676809902268, 592197066758793
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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a(n)/a(n-1) tends to (7+sqrt(13))/2 = 5.30277563...
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FORMULA
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G.f.: (1-4x)/(1-7x+9x^2). a(n)=Sum_{k, 0<=k<=n}A165253(n,k)*3^(n-k).
a(n) = ((13-sqrt(13))*(7+sqrt(13))^n+(13+sqrt(13))*(7-sqrt(13))^n )/(26*2^n). [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Sep 26 2009]
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CROSSREFS
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Sequence in context: A027140 A110309 A101106 this_sequence A133158 A047891 A151498
Adjacent sequences: A165307 A165308 A165309 this_sequence A165311 A165312 A165313
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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), Sep 14 2009
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