A147554 Primes p such that p^2 divides p.p.p where dot "." means concatenation.

3, 13, 37, 9901, 333667, 99990001, 999999000001, 9999999900000001, 13168164561429877, 130654897808007778425046117

Offset

1,1

Comments

Primes p dividing 10^(2*d)+10^d+1 where d=ceiling(log(p)/log(10)) is the number of decimal digits in p. - Max Alekseyev

a(11) > 10^156. - Max Alekseyev, Feb 08 2021

There is no prime p such that p^2 divides p.p.

All primes of the forms 10^(2m) - 10^m + 1 or (1/3)*(10^(2m) + 10^m + 1) are in the sequence.

Primes in A243162. - Hans Havermann, May 31 2014

Links

Table of n, a(n) for n=1..10.

Crossrefs

Cf. A147553, A243162.

Sequence in context: A120479 A146227 A019007 * A076800 A277411 A054975

Adjacent sequences: A147551 A147552 A147553 * A147555 A147556 A147557

Keyword

nonn,base,more

Author

Farideh Firoozbakht, Dec 26 2008

Status

approved