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Search: id:A015520
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| A015520 |
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Linear 2nd order recurrence. |
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+0
2
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| 0, 1, 2, 15, 52, 269, 1110, 5179, 22568, 102105, 452458, 2028071, 9033180, 40375141, 180115262, 804357075, 3589982032, 16027891889, 71545586130, 319397983039, 1425797413508, 6364972640445, 28413716829478
(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) = 2 a(n-1) + 11 a(n-2).
E.g.f. : exp(x)sinh(2sqrt(3)x)/(2sqrt(3)) - Paul Barry (pbarry(AT)wit.ie), Nov 20 2003
a(n)=sum{k=0..n, binomial(n, 2k+1)12^k} - Paul Barry (pbarry(AT)wit.ie), Sep 29 2004
O.g.f.: -x/(-1+2*x+11*x^2). a(n)=11^n*(A^n-B^n)/(4sqrt(3)) where A=1/(2sqrt(3)-1) and B=-1/(2sqrt(3)+1) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 29 2008
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CROSSREFS
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Sequence in context: A066562 A073877 A007972 this_sequence A098520 A056078 A088979
Adjacent sequences: A015517 A015518 A015519 this_sequence A015521 A015522 A015523
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (ogerard(AT)ext.jussieu.fr)
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