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.

1, 2, 4, 31, 62, 124, 601, 1202, 2404, 2593, 4808, 5186, 9616, 10372, 18631, 20744, 37262, 41488, 74524, 82976, 149048, 165952, 298096, 331904, 599479, 1198958, 2397916, 204700049, 409400098, 466344409, 668731841, 818800196, 932688818, 1023500245, 1337463682, 1554449047

Offset: 1

Author

Michel Marcus, May 03 2020

Keywords

• nonn
• base

Comments

Numbers m such that A334487(m) = 1.

Links

• Ray Chandler, Table of n, a(n) for n = 1..56 (first 45 terms from Giovanni Resta)
• Robert G. Wilson v and Ray Chandler, Known terms (not exhaustive)

Crossrefs

Cf. A007733, A007736, A007732, A334487.

Programs

PARI

a2(n) = znorder(Mod(2,n/2^valuation(n,2))); \\ A007733
a5(n) = znorder(Mod(5,n/5^valuation(n,5))); \\ A007736
a10(n) = znorder(Mod(10,n/2^valuation(n,2)/5^valuation(n,5))); \\ A007732
isok(m) = a2(m)*a5(m) == a10(m);

Extensions

a(28) from Jinyuan Wang, May 03 2020

a(29)-a(36) from Giovanni Resta, May 04 2020