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A189641
Partial sums of A189640.
3
0, 0, 1, 1, 1, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 7, 7, 8, 9, 9, 10, 10, 10, 11, 12, 12, 13, 13, 13, 14, 14, 14, 15, 16, 16, 17, 17, 17, 18, 18, 18, 19, 20, 20, 21, 22, 22, 23, 23, 23, 24, 25, 25, 26, 27, 27, 28, 28, 28, 29, 30, 30, 31, 31, 31, 32, 32, 32, 33, 34, 34, 35, 36, 36, 37, 37, 37, 38, 39, 39, 40
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
Cf. A189640, A189672 (essentially the same).
Sequence in context: A368910 A196376 A156077 * A189672 A058889 A226143
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 24 2011
STATUS
approved