A232066 - OEIS

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

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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.