OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
Index entries for linear recurrences with constant coefficients, signature (6,-11,6).
FORMULA
a(n) = 4*3^n-4*2^n+1.
a(n) = 6*a(n-1)-11*a(n-2)+6*a(n-3). - Colin Barker, Feb 22 2015
G.f.: -x*(6*x^2-9*x+5) / ((x-1)*(2*x-1)*(3*x-1)). - Colin Barker, Feb 22 2015
MAPLE
f:=n->4*3^n-4*2^n+1;
PROG
(PARI) Vec(-x*(6*x^2-9*x+5)/((x-1)*(2*x-1)*(3*x-1)) + O(x^100)) \\ Colin Barker, Feb 22 2015
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Aleksandar M. Janjic and Milan Janjic, Feb 08 2007
STATUS
approved