A158899 These are numbers n such that the reciprocal, 1/n, is a repeating fraction whose period is n/2 - 1.

14, 34, 38, 46, 58, 94, 118, 122, 194, 218, 226, 262, 298, 334, 358, 362, 386, 446, 458, 466, 514, 526, 538, 626, 674, 734, 758, 766, 778, 838, 866, 922, 974, 982, 998, 1006, 1018, 1082, 1142, 1154, 1186, 1238, 1294, 1318, 1402, 1418, 1454, 1486, 1622, 1642

Offset

1,1

Comments

These numbers relate to the long period primes, those that for 1/m the period is m-1 (sequence A006883) in that by multiplying each term in the long period primes by 2, this sequence is generated.

Links

Table of n, a(n) for n=1..50.

Prog

(PARI) forstep(n=2, 2e3, 2, if ((setminus(Set(factor(n)[, 1]), Set([2, 5])) != []) && (znorder(Mod(10, n/2^valuation(n, 2)/5^valuation(n, 5))) + 1 == n/2), print1(n, ", ")); ); \\ Michel Marcus, Feb 24 2013

Crossrefs

Cf. A006883, A007732, A085837, A121090.

Sequence in context: A182180 A112878 A175559 * A085777 A329062 A072566

Adjacent sequences: A158896 A158897 A158898 * A158900 A158901 A158902

Keyword

nonn,base

Author

Robert Hutchins, Mar 29 2009

Extensions

More terms and edited by Michel Marcus, Feb 24 2013

Status

approved