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A043530
Number of distinct base-3 digits of n.
4
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
1,3
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
MATHEMATICA
Table[Length[Union[IntegerDigits[n, 3]]], {n, 90}] (* Harvey P. Dale, May 13 2020 *)
PROG
(PARI) a(n) = #vecsort(digits(n, 3), , 8); \\ Michel Marcus, May 16 2016
CROSSREFS
KEYWORD
nonn,base
STATUS
approved