OFFSET
0,2
FORMULA
a(n) = 2(a(n-1)+3^n)+n-1, a(0)=1.
a(n) = 2*3^(n+1)-2^(n+2)-n-1. - Benoit Cloitre, May 23 2004
PROG
(PARI) a(n)=2*3^(n+1)-2^(n+2)-n-1
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, May 14 2004
STATUS
approved