OFFSET
1,3
FORMULA
a(1)=1; a(n+1) = 3*a(n)+(-1)^n*(n+2); a(n)=floor((5/16)*3^(n-1)-(-1)^n*n/4+1/2)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Nov 02 2002
STATUS
approved