OFFSET
1,2
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
FORMULA
a(n) = (4/15)*n^5 + (11/24)*n^4 + (1/4)*n^3 + (1/24)*n^2 - (1/16)*n.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).
G.f.: x*(1 + 12*x + 16*x^2 + 3*x^3)/(1 - x)^6.
MATHEMATICA
(See A213561.)
LinearRecurrence[{6, -15, 20, -15, 6, -1}, {1, 18, 109, 407, 1152, 2723}, 30] (* Harvey P. Dale, Nov 12 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 18 2012
STATUS
approved