A290016 - OEIS

%I #18 Jul 24 2020 07:12:49

%S 24,36,42,54,66,70,78,88,100,102,104,105,124,128,130,135,136,138,152,

%T 154,165,171,172,174,182,184,186,189,190,195,196,225,230,231,232,238,

%U 242,246,248,250,256,258,272,282,286,290,292,296,297,310,318,322,328,333,344,345

%N Brazilian numbers which have exactly three Brazilian representations.

%C These numbers could be called 3-Brazilian numbers.

%C All these numbers are composite with six to ten different divisors.

%C The smallest number of this sequence is 24 with 24 = 44_5 = 33_7 = 22_11. The number 24 is highly Brazilian in A329383.

%e 36 = 4 * 9 = 44_8 = 3 * 12 = 33_11 = 2 * 18 = 22_19.

%e 42 = 2 * 21 = 22_20 = 222_4 = 3 * 14 = 33_13.

%e 124 = 4 * 31 = 44_30 = 444_5 = 2 * 62 = 22_61.

%e 272 = 8 * 34 = 88_33 = 4 * 68 = 44_67 = 2 * 136 = 22_135.

%t Flatten@ Position[#, 3] &@ Table[Count[Range[2, n - 2], _?(And[Length@ # != 1, Length@ Union@ # == 1] &@ IntegerDigits[n, #] &)], {n, 350}] (* _Michael De Vlieger_, Jul 30 2017 *)

%Y Cf. A125134, A220570, A220571, A257521, A288783, A290015, A290017, A290018, A329383.

%K nonn

%O 1,1

%A _Bernard Schott_, Jul 27 2017