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A031948 Numbers with exactly two distinct base-3 digits. 7
3, 5, 6, 7, 9, 10, 12, 14, 16, 17, 18, 20, 22, 23, 24, 25, 27, 28, 30, 31, 36, 37, 39, 41, 43, 44, 49, 50, 52, 53, 54, 56, 60, 62, 67, 68, 70, 71, 72, 74, 76, 77, 78, 79, 81, 82, 84, 85, 90, 91, 93, 94, 108, 109, 111, 112, 117, 118, 120, 122 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MAPLE
filter:= n -> nops(convert(convert(n, base, 3), set))=2:
select(filter, [$1..200]); # Robert Israel, Nov 29 2017
MATHEMATICA
Select[Range[150], Length[Union[IntegerDigits[#, 3]]]==2&] (* Harvey P. Dale, Nov 25 2023 *)
CROSSREFS
Cf. A007089.
Sequence in context: A099467 A054353 A284555 * A247523 A169957 A165712
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified April 16 20:42 EDT 2024. Contains 371754 sequences. (Running on oeis4.)