A242824 Primes formed by the initial digits of the decimal expansion of 1/7, starting at the first nonzero digit in the expansion.

1428571, 1428571428571428571428571

Offset: 1

Author

Felix Fröhlich, May 23 2014

Keywords

• nonn
• base

Comments

Next term has 355 digits.

All terms are of the form 6x+1; a(4) has 823 digits; and there are no further terms up to and including 10000 digits. - Harvey P. Dale, Oct 03 2018

Links

• Amiram Eldar, Table of n, a(n) for n = 1..4

Crossrefs

Cf. A020806, A241217.

Corresponding sequences for 1/k: A093676 (k=12), A242826 (k=13), A242827 (k=14), A242828 (k=17), A242833 (k=19).

Programs

Mathematica

Select[Table[FromDigits[PadRight[{},6n+1,{1,4,2,8,5,7}]],{n,200}],PrimeQ](* Harvey P. Dale, Oct 03 2018 *)