OFFSET
1,2
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..500
Index entries for linear recurrences with constant coefficients, signature (9,-33,63,-66,36,-8).
FORMULA
a(n) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6).
G.f.: x*(1 - 2*x^2) / ((1 - x)^3*(1 - 2*x)^3).
a(n) = (1/2)*((1+n)*(4-2^(2+n) + n + 2^(1+n)*n)). - Colin Barker, Oct 30 2017
MATHEMATICA
(See A213747.)
LinearRecurrence[{9, -33, 63, -66, 36, -8}, {1, 9, 46, 180, 603, 1827}, 30] (* Harvey P. Dale, May 16 2013 *)
PROG
(PARI) Vec(x*(1 - 2*x^2) / ((1 - x)^3*(1 - 2*x)^3) + O(x^30)) \\ Colin Barker, Oct 30 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 19 2012
STATUS
approved