A284758 The least positive integer that has exactly n different representations as Brazilian number.

1, 7, 15, 24, 40, 60, 144, 120, 180, 336, 420, 360, 900, 960, 720, 840, 1260, 1440, 2340, 1680, 2880, 3600, 8190, 2520, 9072, 9900, 6300, 6720, 20592, 5040, 10920, 7560, 31320, 98040, 25920, 10080, 21420, 177156, 74256, 15120, 28560, 20160

Offset

0,2

Comments

The representation n = 11_(n-1) is not accepted under the definition of a Brazilian number.

The records of this sequence are the highly Brazilian numbers; hence, this sequence is a supersequence of A329383.

References

D. Lignon, Dictionnaire de (presque) tous les nombres entiers, Ellipses, 2012, page 420.

Links

Giovanni Resta, Table of n, a(n) for n = 0..100

Example

a(0) = 1 because 1 is the smallest non-Brazilian number.
a(4) = 40 because 40 = 1111_3 = 55_7 = 44_9 = 22_19 and 40 is the smallest integer with four Brazilian representations.

Mathematica

rep[n_] := Length@ Select[Range[2, n/2], 1 == Length@ Union@ IntegerDigits[n, #] &]; a[n_] := Block[{k=1}, While[rep[k] != n, k++]; k]; a /@ Range[0, 15] (* Giovanni Resta, Apr 04 2017 *)

Crossrefs

Cf. A066460, A125134, A329383.

Sequence in context: A076796 A056119 A329383 * A334798 A211430 A082111

Adjacent sequences: A284755 A284756 A284757 * A284759 A284760 A284761

Keyword

nonn,base

Author

Bernard Schott, Apr 04 2017

Status

approved