A244042 In ternary representation of n, replace 2's with 0's.

0, 1, 0, 3, 4, 3, 0, 1, 0, 9, 10, 9, 12, 13, 12, 9, 10, 9, 0, 1, 0, 3, 4, 3, 0, 1, 0, 27, 28, 27, 30, 31, 30, 27, 28, 27, 36, 37, 36, 39, 40, 39, 36, 37, 36, 27, 28, 27, 30, 31, 30, 27, 28, 27, 0, 1, 0, 3, 4, 3, 0, 1, 0, 9, 10, 9, 12, 13, 12, 9, 10, 9

Offset: 0

Author

Joonas Pohjonen, Jun 17 2014

Keywords

• nonn
• base
• look

Examples

			16 = 121_3, replacing 2 with 0 gives 101_3 = 10, so a(16) = 10.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..6560

Crossrefs

Cf. A004488, A117966, A005836, A289813, A289814.

Programs

Maple

a:= proc(n) local t, r, i; t, r:= n, 0;
      for i from 0 while t>0 do
        r:= r+3^i*(d-> `if`(d=2, 0, d))(irem(t, 3, 't'))
      od; r
    end:
seq(a(n), n=0..80);  # Alois P. Heinz, Jun 17 2014

Mathematica

Array[FromDigits[IntegerDigits[#, 3] /. 2 -> 0, 3] &, 72, 0] (* Michael De Vlieger, Mar 17 2018 *)

PARI

a(n) = my(d=digits(n, 3)); fromdigits(apply(x->(if (x==2, 0, x)), d), 3); \\ Michel Marcus, Jun 10 2017

Python

from sympy.ntheory.factor_ import digits
def a(n):return int("".join(map(str, digits(n, 3)[1:])).replace('2', '0'), 3) # Indranil Ghosh, Jun 10 2017

Formula

a(n) = n - 2 * A005836(A289814(n) + 1) = A005836(A289813(n) + 1). - Andrey Zabolotskiy, Nov 11 2019