

A306424


Numbers n such that the baseb expansion of n for each b = 3..n1 never contains more than two distinct digits.


0



1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 16, 17, 20, 22, 23, 25, 26, 31, 37, 43
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OFFSET

1,2


COMMENTS

Conjecture: The sequence is finite, with 43 being the last term.
I checked the conjecture to 10809638.


LINKS

Table of n, a(n) for n=1..23.


EXAMPLE

10 is a term of the sequence, since the baseb expansions of 10 for b = 3..9 are 101, 22, 20, 14, 13, 12, 11, respectively, and none of those expansions contain more than two distinct digits.


MATHEMATICA

Select[Range@ 100, Max@ Table[Length@ Union@ IntegerDigits[#, b], {b, 3, #  1}] <= 2 &] (* Michael De Vlieger, Feb 15 2019 *)


PROG

(PARI) is(n) = for(b=3, n1, my(d=digits(n, b)); if(#vecsort(d, , 8) > 2, return(0))); 1


CROSSREFS

Sequence in context: A154314 A239348 A191881 * A005524 A191890 A247814
Adjacent sequences: A306421 A306422 A306423 * A306425 A306426 A306427


KEYWORD

nonn,base,more


AUTHOR

Felix FrÃ¶hlich, Feb 14 2019


STATUS

approved



