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A284758 The least positive integer that has exactly n different representations as Brazilian number. 6

%I #34 Jul 27 2020 11:20:15

%S 1,7,15,24,40,60,144,120,180,336,420,360,900,960,720,840,1260,1440,

%T 2340,1680,2880,3600,8190,2520,9072,9900,6300,6720,20592,5040,10920,

%U 7560,31320,98040,25920,10080,21420,177156,74256,15120,28560,20160

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

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

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

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

%H Giovanni Resta, <a href="/A284758/b284758.txt">Table of n, a(n) for n = 0..100</a>

%e a(0) = 1 because 1 is the smallest non-Brazilian number.

%e a(4) = 40 because 40 = 1111_3 = 55_7 = 44_9 = 22_19 and 40 is the smallest integer with four Brazilian representations.

%t 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 *)

%Y Cf. A066460, A125134, A329383.

%K nonn,base

%O 0,2

%A _Bernard Schott_, Apr 04 2017

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Last modified March 29 05:48 EDT 2024. Contains 371265 sequences. (Running on oeis4.)