OFFSET
0,2
COMMENTS
Companion to A135343.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,4,-1,3,4).
FORMULA
4*a(n) - a(n+1) = hexaperiodic 0, 3, 1, 0, -3, -1.
a(n) = (4^(n+1)/5)-(2/15)*(-1)^n+(1/3)*cos(Pi*n/3)+(sqrt(3)/3)*cos(Pi*n/3). - Richard Choulet, Jan 04 2008
G.f.: ( -2*(3 + sqrt(3)) + (3 + 7*sqrt(3))*x + (9 + 5*sqrt(3))*x^2 -
4*(3 + sqrt(3))*x^3)/( 6*(-1 + 4*x - x^3 + 4*x^4) ). - G. C. Greubel, Oct 10 2016
G.f.: (1-3*x^2) / ((1+x)*(1-4*x)*(1-x+x^2)). - Colin Barker, Oct 11 2016
MATHEMATICA
LinearRecurrence[{3, 4, -1, 3, 4}, {1, 4, 13, 51, 204}, 25] (* G. C. Greubel, Oct 10 2016 *)
PROG
(PARI) Vec((1-3*x^2)/((1+x)*(1-4*x)*(1-x+x^2)) + O(x^30)) \\ Colin Barker, Oct 11 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Dec 06 2007
EXTENSIONS
Removed incorrect formula, Joerg Arndt, Oct 11 2016
STATUS
approved