OFFSET
1,1
EXAMPLE
Writing (i,j) for i+r*j, the first 7 in the ranking are
(0,0), (1,0), (0,1), (2,0), (1,1), (3,0), (0,2);
the rank where i and j are both odd is a(1)=5.
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 08 2011
STATUS
approved