OFFSET
1,3
COMMENTS
See A189727.
FORMULA
s(n)=s([(n+2)/3])+[(n+1)/3]+[n/3]-s([n/3]), where s(0)=0, s(1)=0.
MATHEMATICA
(See A189727.)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 26 2011
STATUS
approved