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A351472 Numbers m such that the largest digit in the decimal expansion of 1/m is 6.

%I A351472 #18 Feb 17 2022 11:41:02
%S A351472 6,15,16,24,39,60,64,88,96,150,156,160,165,219,240,246,273,275,375,
%T A351472 378,384,390,399,462,600,606,615,624,625,640,792,822,858,880,888,956,
%U A351472 960,975,984,1500,1515,1536,1554,1560,1584,1596,1600,1606,1626,1628,1638,1650,1665,1776,2145
%N A351472 Numbers m such that the largest digit in the decimal expansion of 1/m is 6.
%C A351472 If k is a term, 10*k is also a term.
%C A351472 First few primitive terms are 6, 15, 16, 24, 39, 64, 88, 96, 156, 165, ...
%C A351472 There is no prime up to 2.6*10^8 (see comments in A333237).
%C A351472 Subsequence: {6, 606, 60606, ...} = 6 * A094028.
%e A351472 1/6 = 0.166666..., and 6 is the smallest number m such that the largest digit in the decimal expansion of 1/m is 6, so a(1) = 6.
%e A351472 As 1/39 = 0.025641025641..., 39 is a term.
%t A351472 f[n_] := Union[ Flatten[ RealDigits[ 1/n][[1]] ]]; Select[Range@1500000, Max@ f@# == 6 &]
%o A351472 (Python)
%o A351472 from itertools import count, islice
%o A351472 from sympy import n_order, multiplicity
%o A351472 def A351472_gen(startvalue=1): # generator of terms >= startvalue
%o A351472     for m in count(max(startvalue, 1)):
%o A351472         m2, m5 = multiplicity(2, m), multiplicity(5, m)
%o A351472         if max(str(10**(max(m2, m5)+n_order(10, m//2**m2//5**m5))//m)) == '6':
%o A351472             yield m
%o A351472 A351472_list = list(islice(A351472_gen(), 20)) # _Chai Wah Wu_, Feb 17 2022
%Y A351472 Similar with largest digit k: A333402 (k=1), A341383 (k=2), A350814 (k=3), A351470 (k=4), A351471 (k=5), this sequence (k=6), A351473 (k=7), A351474 (k=8), A333237 (k=9).
%Y A351472 Cf. A094028, A333236.
%K A351472 nonn,base
%O A351472 1,1
%A A351472 _Bernard Schott_ and _Robert G. Wilson v_, Feb 16 2022