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

1,2

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)

Prog

(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);

Crossrefs

Cf. A007733, A007736, A007732, A334487.

Sequence in context: A132473 A053037 A018294 * A296249 A181620 A220283

Adjacent sequences: A334485 A334486 A334487 * A334489 A334490 A334491

Keyword

nonn,base

Author

Michel Marcus, May 03 2020

Extensions

a(28) from Jinyuan Wang, May 03 2020

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

Status

approved