OFFSET
1,1
EXAMPLE
f(1,1)=3, f(1,2)=7, f(1,3)=15, so a(1)=3.
For n=1,2,3,4,5, the first few f's follow:
1: 3,7,15,31,63
2: 5,11,23,47,95
3: 7,15,31,63,127
4: 9,19,39,77,159
5: 11,23,47,95,191
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Clark Kimberling, Oct 07 2008
STATUS
approved