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A168579 G.f.: 1/(1-x-16*x^2). 3
1, 1, 17, 33, 305, 833, 5713, 19041, 110449, 415105, 2182289, 8823969, 43740593, 184924097, 884773585, 3843559137, 17999936497, 79496882689, 367495866641, 1639445989665, 7519379855921, 33750515690561, 154060593385297 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The ratio a(n+1)/a(n) converges to (1+sqrt(65))/2 as n approaches infinity. - Felix P. Muga II, Mar 12 2014

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,16).

FORMULA

a(0)=a(1)=1, a(n) = a(n-1) + 16*a(n-2) for n>1.

a(n) = (1/sqrt(65))*( ((1+sqrt(65))/2)^(n+1) - ((1-sqrt(65))/2)^(n+1) ), for n >= 0 [Binet representation] - Felix P. Muga II, Mar 12 2014

E.g.f.: (1/sqrt(65))*exp(x/2)*( sinh((sqrt(65)/2)*x) + sqrt(65)*cosh((sqrt(65)/2) *x) ). - G. C. Greubel, Jul 26 2016

MATHEMATICA

Join[{a=1, b=1}, Table[c=1*b+16*a; a=b; b=c, {n, 60}]] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2011 *)

CoefficientList[Series[1/(1 - x - 16 x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Mar 14 2014 *)

LinearRecurrence[{1, 16}, {1, 1}, 30] (* Harvey P. Dale, Aug 14 2014 *)

PROG

(PARI) a(n)=([0, 1; 16, 1]^n*[1; 1])[1, 1] \\ Charles R Greathouse IV, Jul 26 2016

CROSSREFS

Sequence in context: A249356 A286679 A116523 * A135637 A040272 A062054

Adjacent sequences:  A168576 A168577 A168578 * A168580 A168581 A168582

KEYWORD

nonn,easy

AUTHOR

Philippe Deléham, Nov 30 2009

STATUS

approved

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Last modified July 22 16:39 EDT 2019. Contains 325224 sequences. (Running on oeis4.)