OFFSET
1,6
COMMENTS
See A189640.
FORMULA
a(n) = a(floor((n+2)/3)) + floor(n/3), where a(1)=0.
MATHEMATICA
(See A189640.)
PROG
(PARI) a(n) = n--; (n - vecsum(digits(n, 3)%2))/2; \\ Kevin Ryde, Apr 23 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 24 2011
STATUS
approved