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

Author

Bernard Schott, Apr 04 2017

Keywords

• nonn
• base

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.

Examples

			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.
		

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

Crossrefs

Cf. A066460, A125134, A329383.

Programs

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 *)