cp's OEIS Frontend

A334929 Positive integers k such that there exists a positive integer m consisting of k identical digits and such that m is a multiple of k.

%I A334929 #22 Oct 04 2021 09:02:22
%S A334929 1,2,3,4,5,6,7,8,9,12,15,18,21,22,24,27,36,42,44,45,54,63,66,72,78,81,
%T A334929 84,88,108,111,126,132,135,156,162,168,189,198,205,216,222,234,242,
%U A334929 243,252,264,294,312,324,333,342,378,396,404,405,444,462,465,468,484,486
%N A334929 Positive integers k such that there exists a positive integer m consisting of k identical digits and such that m is a multiple of k.
%C A334929 For k=3^t, t>=1 you can always find numbers m.
%e A334929 12 is a term since 444444444444 = 12*37037037037.
%t A334929 ok[n_] := AnyTrue[(10^n - 1)/9 Range@9, Mod[#, n] == 0 &]; Select[ Range[486], ok] (* _Giovanni Resta_, May 24 2020 *)
%o A334929 (Python)
%o A334929 t = "1"
%o A334929 list = [1]
%o A334929 for i in range(1, 1000):
%o A334929     t = "1" + t
%o A334929     m = int(t)
%o A334929     weiter = 0
%o A334929     for k in range(1, 10):
%o A334929         if k * m % (i + 1) == 0:
%o A334929             weiter = 1
%o A334929     if weiter == 1:
%o A334929         list.append(i + 1)
%o A334929 print(list)
%Y A334929 Cf. A014950.
%K A334929 nonn,base
%O A334929 1,2
%A A334929 _Reiner Moewald_, May 16 2020