OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
J. P. McSorley, Counting structures in the Moebius ladder, Discrete Math., 184 (1998), 137-164.
Index entries for linear recurrences with constant coefficients, signature (16,-87,200,-208,96,-16).
FORMULA
a(n) = (4+sqrt(12))^n+(4-sqrt(12))^n+2^n-(5/2+1/2*sqrt(17))^n-(5/2-1/2*sqrt(17))^n-1.
G.f.: 2*x*(2-13*x+34*x^2-28*x^3+8*x^4) / ( (x-1)*(2*x-1)*(4*x^2-8*x+1)*(2*x^2-5*x+1) ).
PROG
(PARI) concat(0, Vec(2*x*(8*x^4-28*x^3+34*x^2-13*x+2)/((x-1)*(2*x-1)*(2*x^2-5*x+1)*(4*x^2-8*x+1)) + O(x^30))) \\ Colin Barker, Aug 02 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved