OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5000
FORMULA
a(n) = (1/6)*n*(109*n^2 - 153*n + 50).
G.f.: x*(1 + 56*x + 52*x^2)/(1-x)^4. - Colin Barker, Jan 19 2012
PROG
(Magma) [(1/6)*(109*n^3-153*n^2+50*n): n in [1..40]]; // Vincenzo Librandi, Jul 19 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
James A. Record (james.record(AT)gmail.com), Nov 07 2004
STATUS
approved