cp's OEIS Frontend

A354745 Non-repdigit numbers k such that every permutation of the digits of k has the same number of divisors.

%I A354745 #27 Jun 09 2022 02:25:38
%S A354745 13,15,17,24,26,31,37,39,42,51,58,62,71,73,79,85,93,97,113,117,131,
%T A354745 155,171,177,178,187,199,226,262,288,311,337,339,355,373,393,515,535,
%U A354745 551,553,558,585,622,711,717,718,733,771,781,817,828,855,871,882,899,919,933,989,991,998
%N A354745 Non-repdigit numbers k such that every permutation of the digits of k has the same number of divisors.
%C A354745 After a(93) = 84444, no further terms < 10^18. - _Michael S. Branicky_, Jun 08 2022
%e A354745 871 is a term because d(871) = d(817) = d(178) = d(187) = d(718) = d(781) = 4, where d(n) is the number of divisors of n.
%t A354745 Select[Range[10000],CountDistinct[DivisorSigma[0,FromDigits /@ Permutations[IntegerDigits[#]]]]==1&&CountDistinct[IntegerDigits[#]]>1&]
%o A354745 (Python)
%o A354745 from sympy import divisor_count
%o A354745 from itertools import permutations
%o A354745 def ok(n):
%o A354745     s, d = str(n), divisor_count(n)
%o A354745     if len(set(s)) == 1: return False
%o A354745     return all(d==divisor_count(int("".join(p))) for p in permutations(s))
%o A354745 print([k for k in range(5500) if ok(k)]) # _Michael S. Branicky_, Jun 05 2022
%Y A354745 Cf. A000005, A003459, A067012, A062895, A350867, A354746.
%K A354745 nonn,base
%O A354745 1,1
%A A354745 _Metin Sariyar_, Jun 05 2022