OFFSET
1,2
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
G.f.: x*(1 + 15*x + 8*x^2)/(1-x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4).
a(n) = (n - 7*n^2 + 8*n^3)/2.
a(n) = Sum_{i = 0..n-1} (n + i)*(n + 3*i). - Bruno Berselli, Feb 14 2018
MATHEMATICA
(See A213831.)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 04 2012
STATUS
approved