A232066 Periodic primes: primes p whose decimal expansion can be written as sss...st, where s is nonempty string of digits not beginning with 0, there are at least two copies of s, and t (which may be absent) is a prefix of s.

11, 18181, 32323, 35353, 72727, 74747, 78787, 94949, 95959, 1041041, 1051051, 1131131, 1191191, 1201201, 1212121, 1221221, 1231231, 1261261, 1281281, 1311311, 1381381, 1401401, 1411411, 1491491, 1501501, 1551551, 1581581, 1616161, 1621621, 1641641, 1671671

Offset

1,1

Comments

The terms > 10^4 in A032758 appear in this sequence.

The terms > 10^20 in A231588 appear in this sequence.

Links

Paul Tek, Table of n, a(n) for n = 1..5972

Paul Tek, PARI program for this sequence

Example

9779779 = 977|977|9,
727272727 = 72|72|72|72|7 = 7272|7272|7.

Prog

(PARI) See Link section.

Crossrefs

Cf. A032758, A231588.

A004022 is a subsequence (these are the terms where s=1 and t is absent). - Harvey P. Dale, Jul 09 2019

Sequence in context: A199148 A248732 A252862 * A330301 A264917 A198668

Adjacent sequences: A232063 A232064 A232065 * A232067 A232068 A232069

Keyword

base,nonn

Author

Paul Tek, Nov 17 2013

Extensions

Definition corrected by N. J. A. Sloane, Jul 09 2019

Status

approved