OFFSET
1,2
FORMULA
a(n) = 2*(n-2)*2^n + n*(n+1)/2 + 4
G.f.: x*(1-4*x^2+4*x^3)/((2*x-1)^2 * (1-x)^3) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009]
PROG
(PARI) a(n)=2*(n-2)*2^n +n*(n+1)/2+4
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 04 2003
EXTENSIONS
G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.
STATUS
approved