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A015454 Generalized Fibonacci numbers. 4
1, 1, 9, 73, 593, 4817, 39129, 317849, 2581921, 20973217, 170367657, 1383914473, 11241683441, 91317382001, 741780739449, 6025563297593, 48946287120193, 397595860259137, 3229713169193289, 26235301213805449, 213112122879636881 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n)/a(n-1) tends to (8 + 2*sqrt(17))/2 = exp ArcSinh 4 = A176458. - Gary W. Adamson, Dec 26 2007

For n>=1, row sums of triangle for numbers 8^k*C(m,k) with duplicated diagonals. - Vladimir Shevelev, Apr 13 2012

For n>=1, a(n) equals the numbers of words of length n-1 on alphabet {0,1,...,8} containing no subwords ii, (i=0,1,...,7). - Milan Janjic, Jan 31 2015

a(n+1) is the number of nonary sequences of length n such that no two consecutive terms have distance 5. - David Nacin, May 31 2017

LINKS

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

M. Janjic, On Linear Recurrence Equations Arising from Compositions of Positive Integers, Journal of Integer Sequences, Vol. 18 (2015), Article 15.4.7.

Tanya Khovanova, Recursive Sequences

Index entries for linear recurrences with constant coefficients, signature (8,1)

FORMULA

a(n) = 8 a(n-1) + a(n-2).

a(n) = Sum_{k, 0<=k<=n} 7^k*A055830(n,k). - Philippe Deléham, Oct 18 2006

G.f.: (1-7*x)/(1-8*x-x^2). [Philippe Deléham, Nov 20 2008]

a(n) = (3/34)*sqrt(17)*[4-sqrt(17)]^n-(3/34)*[4+sqrt(17)]^n*sqrt(17)+(1/2)*[4+sqrt(17)]^n+(1/2) *[4-sqrt(17)]^n, with n>=0. [Paolo P. Lava, Nov 21 2008]

For n>=2, a(n) = F_n(8)+F_(n+1)(8), where F_n(x) is Fibonacci polynomial (cf.A049310): F_n(x) = Sum_{i=0..floor((n-1)/2)} C(n-i-1,i)x^(n-2*i-1). - Vladimir Shevelev, Apr 13 2012

a(n) = A041025(n) -7*A041025(n-1). - R. J. Mathar, Jul 06 2012

MATHEMATICA

LinearRecurrence[{8, 1}, {1, 1}, 30] (* Vincenzo Librandi, Nov 08 2012 *)

PROG

(MAGMA) [n le 2 select 1 else 8*Self(n-1) + Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 08 2012

CROSSREFS

Row m=8 of A135597.

Sequence in context: A164588 A023001 A277672 * A121246 A086226 A199677

Adjacent sequences:  A015451 A015452 A015453 * A015455 A015456 A015457

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified November 18 12:21 EST 2017. Contains 294891 sequences.