A105186 Replace odd-positioned digits with 0 in ternary representation of n.

0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 81, 82

Offset

0,3

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Formula

a(n) = n - a(floor(n/3))*3, a(0) = 0.

a(n) = 9*a(floor(n/9)) + (n mod 9) mod 3. - Reinhard Zumkeller, Sep 26 2015

Example

n = 123 = '11120' --> '10100' = 90 = a(123).

Prog

(Haskell)
a105186 0 = 0
a105186 n = 9 * a105186 n' + mod t 3
            where (n', t) = divMod n 9
-- Reinhard Zumkeller, Sep 26 2015
(PARI) a(n) = fromdigits(digits(n, 9)%3, 9); \\ Kevin Ryde, May 20 2020

Crossrefs

Cf. A007089, A063694, A163325.

Sequence in context: A025685 A194515 A163325 * A328346 A238406 A058709

Adjacent sequences: A105183 A105184 A105185 * A105187 A105188 A105189

Keyword

nonn,base

Author

Reinhard Zumkeller, Apr 11 2005

Status

approved