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Search: id:A015537
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| A015537 |
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Linear 2nd order recurrence. |
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+0
4
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| 0, 1, 5, 29, 165, 941, 5365, 30589, 174405, 994381, 5669525, 32325149, 184303845, 1050819821, 5991314485, 34159851709, 194764516485, 1110461989261, 6331368012245, 36098688018269, 205818912140325, 1173489312774701
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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First differences give A122690(n) = {1, 4, 24, 136, 776, 4424, 25224, ...}. Partial sums of a(n) are {0, 1, 6, 35, 200, ...} = (A123270(n) - 1)/8. - Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 03 2006
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FORMULA
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a(n) = 5 a(n-1) + 4 a(n-2).
a(n)=sum{k=0..floor((n-1)/2), C(n-k-1, k)4^k*5^(n-2k-1)} - Paul Barry (pbarry(AT)wit.ie), Apr 23 2005
a(n) = Sum[ A122690(k), {k,0,n-1} ] for n>0. - Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 03 2006
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CROSSREFS
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Cf. A122690, A123270.
Adjacent sequences: A015534 A015535 A015536 this_sequence A015538 A015539 A015540
Sequence in context: A065541 A060926 A098780 this_sequence A141812 A001653 A141814
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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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