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A334488 Numbers m for which p(m, 2)*p(m, 5) = p(m, 10), where p(m, b) is the period of repeating digits of 1/m in base b.

%I A334488 #31 May 15 2020 11:41:51
%S A334488 1,2,4,31,62,124,601,1202,2404,2593,4808,5186,9616,10372,18631,20744,
%T A334488 37262,41488,74524,82976,149048,165952,298096,331904,599479,1198958,
%U A334488 2397916,204700049,409400098,466344409,668731841,818800196,932688818,1023500245,1337463682,1554449047
%N A334488 Numbers m for which p(m, 2)*p(m, 5) = p(m, 10), where p(m, b) is the period of repeating digits of 1/m in base b.
%C A334488 Numbers m such that A334487(m) = 1.
%H A334488 Ray Chandler, <a href="/A334488/b334488.txt">Table of n, a(n) for n = 1..56</a> (first 45 terms from Giovanni Resta)
%H A334488 Robert G. Wilson v and Ray Chandler, <a href="/A334488/a334488_2.txt">Known terms (not exhaustive)</a>
%o A334488 (PARI)
%o A334488 a2(n) = znorder(Mod(2,n/2^valuation(n,2))); \\ A007733
%o A334488 a5(n) = znorder(Mod(5,n/5^valuation(n,5))); \\ A007736
%o A334488 a10(n) = znorder(Mod(10,n/2^valuation(n,2)/5^valuation(n,5))); \\ A007732
%o A334488 isok(m) = a2(m)*a5(m) == a10(m);
%Y A334488 Cf. A007733, A007736, A007732, A334487.
%K A334488 nonn,base
%O A334488 1,2
%A A334488 _Michel Marcus_, May 03 2020
%E A334488 a(28) from _Jinyuan Wang_, May 03 2020
%E A334488 a(29)-a(36) from _Giovanni Resta_, May 04 2020