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A147554 Primes p such that p^2 divides p.p.p where dot "." means concatenation. 2
3, 13, 37, 9901, 333667, 99990001, 999999000001, 9999999900000001, 13168164561429877, 130654897808007778425046117 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 3 20:26 EST 2022. Contains 358543 sequences. (Running on oeis4.)