A189641 Partial sums of A189640.

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.

Links

Table of n, a(n) for n=1..81.

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

Adjacent sequences: A189638 A189639 A189640 * A189642 A189643 A189644

Keyword

nonn

Author

Clark Kimberling, Apr 24 2011

Status

approved