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A041085
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Denominators of continued fraction convergents to sqrt(50).
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13
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1, 14, 197, 2772, 39005, 548842, 7722793, 108667944, 1529074009, 21515704070, 302748930989, 4260000737916, 59942759261813, 843458630403298, 11868363584907985, 167000548819115088, 2349876047052519217, 33065265207554384126, 465263588952813896981
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OFFSET
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0,2
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COMMENTS
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For positive n, a(n) equals the permanent of the n X n tridiagonal matrix with 14's along the main diagonal, and 1's along the superdiagonal and the subdiagonal. - John M. Campbell, Jul 08 2011
a(n) equals the number of words of length n on alphabet {0,1,...,14} avoiding runs of zeros of odd lengths. - Milan Janjic, Jan 28 2015
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..800
Tanya Khovanova, Recursive Sequences
Index entries for linear recurrences with constant coefficients, signature (14,1).
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FORMULA
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a(n) = round((7+5*sqrt(2))*a(n-1)). - Vladeta Jovovic, Jun 15 2003
a(n) = A000129(3n+3)/5. a(n) = (1+sqrt(2))^(3*n)*(1/2+7*sqrt(2)/20)+(1-sqrt(2))^(3*n)*(1/2-7*sqrt(2)/20). a(n) = sum{i=0..n, sum{j=0..n, (n!/(i!j!(n-i-j)!)*A000129(2n-i)/5}}. - Paul Barry, Feb 06 2004
a(n) = F(n, 14), the n-th Fibonacci polynomial evaluated at x=14. - T. D. Noe, Jan 19 2006
From Philippe Deléham, Nov 03 2008: (Start)
a(n) = 14*a(n-1)+a(n-2); a(0)=1, a(1)=14.
G.f.: 1/(1-14*x-x^2). (End)
a(n) = ((7+5*sqrt(2))^(n+1)-(7-5*sqrt(2))^(n+1))/(10*sqrt(2)). - Gerry Martens, Jul 11 2015
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MAPLE
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with (combinat):seq(fibonacci(3*n, 2)/5, n=1..17); # Zerinvary Lajos, Apr 20 2008
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MATHEMATICA
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LinearRecurrence[{14, 1}, {1, 14}, 30] (* Vincenzo Librandi, Nov 17 2012 *)
Table[Fibonacci[3n + 3, 2]/5, {n, 0, 20}] (* Vladimir Reshetnikov, Sep 16 2016 *)
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PROG
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(MAGMA) I:=[1, 14]; [n le 2 select I[n] else 14*Self(n-1) +Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 17 2012
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CROSSREFS
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Cf. A041084, A040042, A020807.
Sequence in context: A278476 A067221 A072533 * A124239 A041366 A051817
Adjacent sequences: A041082 A041083 A041084 * A041086 A041087 A041088
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KEYWORD
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nonn,cofr,easy,frac
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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Additional term from Colin Barker, Nov 12 2013
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STATUS
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approved
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