OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).
FORMULA
a(n)= 2*a(n-3) - a(n-6).
a(3*n) + a(1+3*n) + a(2+3*n) = 5+9*n.
a(n) = n + 1 - (-1)^n*A099254(n-1). - R. J. Mathar, Mar 31 2011
G.f.: ( 1+3*x+x^2+3*x^3+x^4 ) / ( (x-1)^2*(1+x+x^2)^2 ). - R. J. Mathar, Mar 31 2011
a(n) = (9*(n+1) + sqrt(3)*(3*n+4)*sin((2*Pi*n)/3) + 3*n*cos((2*Pi*n)/3)) / 9. - Colin Barker, Mar 06 2017
MATHEMATICA
CoefficientList[Series[(1+3x+x^2+3x^3+x^4)/((x-1)^2(1+x+x^2)^2), {x, 0, 85}], x] (* Harvey P. Dale, Apr 09 2011 *)
PROG
(PARI) Vec((1+3*x+x^2+3*x^3+x^4 ) / ((x-1)^2*(1+x+x^2)^2) + O(x^100)) \\ Colin Barker, Mar 06 2017
CROSSREFS
KEYWORD
nonn,less,easy
AUTHOR
Paul Curtz, Mar 22 2011
STATUS
approved