OFFSET
1,2
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (8,-26,44,-41,20,-4).
FORMULA
a(n) = (1/6)*(84 - 21*2^(n+2) + 23*n + 9*n*2^(n+2) - 3*n^2 - 2*n^3).
a(n) = 8*a(n-1) - 26*a(n-2) + 44*a(n-3) - 41*a(n-4) + 20*a(n-5) - 4*a(n-6).
G.f.: f(x)/g(x), where f(x) = x*(1 + x - 2*x^2 - 2*x^3) and g(x) = (1 - x)^4 * (1 - 2*x)^2.
MATHEMATICA
(See A213753.)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 20 2012
STATUS
approved