OFFSET
7,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (3, -3, 1, 0, 1, -3, 3, -1).
FORMULA
a(n)=(n + 7)*(n^2 + 35*n + 90)/30 - 1/5*(1 + ( - 1/2 + 3/10*5^(1/2))*cos(2*n*Pi/5) + (1/5*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/10*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(2*n*Pi/5) + ( - 1/2 - 3/10*5^(1/2))*cos(4*n*Pi/5) + ( - 1/10*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/5*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(4*n*Pi/5)) - Richard Choulet, Dec 14 2008
a(n)= 3*a(n-1) -3*a(n-2) +a(n-3) +a(n-5) -3*a(n-6) +3*a(n-7) -a(n-8). G.f.: -x^7*(-21+30*x-13*x^2+x^3+20*x^5-29*x^6+11*x^7)/( (x^4+x^3+x^2+x+1) * (x-1)^4). - R. J. Mathar, Oct 05 2009
MATHEMATICA
LinearRecurrence[{3, -3, 1, 0, 1, -3, 3, -1}, {21, 33, 49, 68, 90, 116, 145, 179}, 60] (* Harvey P. Dale, Sep 10 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Corrected by T. D. Noe, Dec 11 2006
STATUS
approved