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A189717
Partial sums of A156595.
5
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
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
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 26 2011
STATUS
approved