A043530 Number of distinct base-3 digits of n.

1, 1, 2, 1, 2, 2, 2, 1, 2, 2, 3, 2, 1, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 1, 2, 2, 3, 2, 2, 3, 3, 3, 3, 2, 2, 3, 2, 1, 2, 3, 2, 2, 3, 3, 3, 3, 2, 2, 3, 2, 2, 2, 3, 2, 3, 3, 3, 2, 3, 2, 3, 3, 3, 3, 2, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 1, 2, 2, 3, 2, 2, 3, 3, 3, 3, 2

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Comments

a(A031944(n)) = 3; a(A154314(n)) < 3. - Reinhard Zumkeller, Jan 07 2009

Image, under the coding sending i -> 1+floor(i/3), of the fixed point, starting with 0, of the morphism 0 -> 012, 1 -> 314, 2 -> 542, 3 -> 336, 4 -> 644, 5 -> 565, 6 -> 666. - Jeffrey Shallit, May 15 2016

Links

• Antti Karttunen, Table of n, a(n) for n = 1..19683

Crossrefs

Cf. A007089, A031944, A037897, A154314.

Programs

Mathematica

Table[Length[Union[IntegerDigits[n,3]]],{n,90}] (* Harvey P. Dale, May 13 2020 *)

PARI

a(n) = #vecsort(digits(n,3),,8); \\ Michel Marcus, May 16 2016