OFFSET
1,1
COMMENTS
Every term is even.
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = (2*n + 5*n^2 + 6*n^3 + 3*n^4)/4 = n*(1 + n)*(2 + 3*n + 3*n^2)/4.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5).
G.f.: f(x)/g(x), where f(x) = 2*x*(2 + 5*x + 2*x^2) and g(x) = (1-x)^5.
a(n) = Sum_{i=1..n} i*(3*i^2+1). - Bruno Berselli, Feb 09 2017
MATHEMATICA
(See A213822.)
PROG
(PARI) a(n) = n*(3*n^3 + 6*n^2 + 5*n + 2)/4 \\ Charles R Greathouse IV, Feb 09 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 04 2012
STATUS
approved