OFFSET
0,1
COMMENTS
A floretion-generated sequence relating Fibonacci numbers.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,2,-1).
FORMULA
a(n) = 2*a(n-1) + 2*a(n-2) - a(n-3), a(0) = 2, a(1) = 5, a(2) = 14.
a(n) + a(n+1) = A100545(n).
a(n) + 2*a(n+1) + a(n+2) = A055849(n+2).
a(n) = (2^(-1-n)*((-1)^n*2^(1+n)+(9-5*sqrt(5))*(3-sqrt(5))^n+(3+sqrt(5))^n*(9+5*sqrt(5))))/5. - Colin Barker, Oct 01 2016
MATHEMATICA
CoefficientList[Series[(x+2)/((x+1)(x^2-3x+1)), {x, 0, 30}], x] (* or *) LinearRecurrence[{2, 2, -1}, {2, 5, 14}, 30] (* Harvey P. Dale, Apr 22 2012 *)
PROG
(PARI) a(n) = round((2^(-1-n)*((-1)^n*2^(1+n)+(9-5*sqrt(5))*(3-sqrt(5))^n+(3+sqrt(5))^n*(9+5*sqrt(5))))/5) \\ Colin Barker, Oct 01 2016
(PARI) Vec((x+2)/((x+1)*(x^2-3*x+1)) + O(x^40)) \\ Colin Barker, Oct 01 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Creighton Dement, Feb 06 2005
EXTENSIONS
Corrected by T. D. Noe, Nov 02 2006, Nov 07 2006
STATUS
approved