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Search: id:A015561
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| A015561 |
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Linear 2nd order recurrence. |
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+0
1
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| 0, 1, 7, 53, 399, 3005, 22631, 170437, 1283583, 9666829, 72802135, 548282261, 4129184367, 31097419613, 234198674759, 1763780401765, 13283257511391, 100037924186797, 753398499353143, 5673941192219189, 42731182342946895
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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a(n) = 7 a(n-1) + 4 a(n-2).
a(n)=-(1/65)*sqrt(65)*[7/2-(1/2)*sqrt(65)]^n+(1/65)*sqrt(65)*[7/2+(1/2)*sqrt(65)]^n , with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jun 25 2008
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CROSSREFS
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Adjacent sequences: A015558 A015559 A015560 this_sequence A015562 A015563 A015564
Sequence in context: A141911 A056590 A065542 this_sequence A133588 A081338 A142981
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (olivier.gerard(AT)gmail.com)
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