A051627 Periods associated with A040017.

1, 2, 3, 4, 10, 12, 9, 14, 24, 36, 48, 38, 19, 23, 39, 62, 120, 150, 106, 93, 134, 294, 196, 320, 654, 738, 385, 586, 317, 597, 1404, 945, 1452, 1836, 1752, 1172, 1812, 1282, 1426, 2232, 1862, 1844, 1521, 2134, 3750, 1031, 2264, 2667, 4354, 3927, 4274, 6522, 3903, 6022, 6682, 6135, 9550, 5877

Offset

1,2

Comments

The numbers in A007498 sorted according to the magnitude of the corresponding prime. - T. D. Noe, Sep 08 2005

Links

Ray Chandler, Table of n, a(n) for n = 1..99

C. K. Caldwell, Unique Primes

Eric Weisstein's World of Mathematics, Unique Prime

Index entries for sequences related to decimal expansion of 1/n

Formula

a(n) = A002371(A000720(A040017(n))). - Max Alekseyev, Oct 14 2022

Example

The decimal expansion of 1/101 is 0.00990099..., having a period of 4 and it is the only prime with that period.

Mathematica

nmax = 10000; primesPeriods = Reap[Do[p = Cyclotomic[n, 10]/GCD[n, Cyclotomic[n, 10]]; If[PrimeQ[p], Print[n]; Sow[{p, n}]], {n, 1, nmax}]][[2, 1]]; Sort[primesPeriods][[All, 2]] // Prepend[#, 1]& // Take[#, 58]& (* Jean-François Alcover, Mar 29 2013 *)

Crossrefs

Sequence in context: A087460 A082866 A085701 * A023725 A250051 A076079

Adjacent sequences: A051624 A051625 A051626 * A051628 A051629 A051630

Keyword

nonn,nice,base

Author

N. J. A. Sloane

Extensions

More terms from Jud McCranie

More terms from T. D. Noe, Sep 08 2005

Corrected a(45)=3750 and extended by Ray Chandler, Oct 13 2008

Status

approved