OFFSET
1,2
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (5,-7,3).
FORMULA
For n>1, a(n) = 10*3^(n-2) - n - 1.
For n>4, a(n) = 5*a(n-1) - 7*a(n-2) + 3*a(n-3). - Colin Barker, Jul 11 2015
G.f.: -x*(x^3-2*x^2+2*x+1) / ((x-1)^2*(3*x-1)). - Colin Barker, Jul 11 2015
PROG
(PARI) Vec(-x*(x^3-2*x^2+2*x+1)/((x-1)^2*(3*x-1)) + O(x^50)) \\ Colin Barker, Jul 11 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved