A189717 Partial sums of A156595.

0, 1, 2, 2, 3, 3, 3, 4, 4, 4, 5, 6, 6, 7, 7, 7, 8, 9, 9, 10, 11, 11, 12, 12, 12, 13, 14, 14, 15, 16, 16, 17, 17, 17, 18, 18, 18, 19, 20, 20, 21, 21, 21, 22, 23, 23, 24, 25, 25, 26, 26, 26, 27, 27, 27, 28, 29, 29, 30, 30, 30, 31, 31, 31, 32, 33, 33, 34, 34, 34, 35, 36, 36, 37, 38, 38, 39, 39, 39, 40, 40

Offset

1,3

Comments

See A156595.

Links

Andrew Howroyd, Table of n, a(n) for n = 1..10000

Kevin Ryde, Iterations of the Terdragon Curve, see index "AltTurnsR".

Formula

a(n) = floor((n+1)/3) + floor(n/3) - a(floor(n/3)), with a(0) = 0.

Mathematica

(See A189715.)

Prog

(PARI) a(n) = {if(n<=0, 0, (n+1)\3 + n\3 - a(n\3))} \\ Andrew Howroyd, Sep 10 2019
(PARI) a(n) = (n - subst(Pol(digits(n, 3)%2), 'x, -1))/2; \\ Kevin Ryde, Jul 18 2021

Crossrefs

Cf. A156595, A189715, A189716.

Sequence in context: A060144 A107347 A320063 * A219519 A330393 A273263

Adjacent sequences: A189714 A189715 A189716 * A189718 A189719 A189720

Keyword

nonn

Author

Clark Kimberling, Apr 26 2011

Status

approved