OFFSET
1,2
COMMENTS
Is a(n+1)-a(n) always 1,2 or 3?
EXAMPLE
The first 20 terms of A131389 are
0,1,2,-1,3,4,-2,-3,6,-4,5,7,-5,8,-6,-7,9,10,-8,11.
Positions occupied by nonnegatives are
1,2,3,5,6,9,11,12,14,17,18,20.
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 03 2010
STATUS
approved