A116899 Numbers k such that (k concatenated k times) + 1 = A000461(k) + 1 is a prime number.

1, 2, 6, 3022

Offset

1,2

Comments

The (probable) prime corresponding to a(4) = 3022, i.e., 3022302230...3023 has 12088 digits.

Next term is greater than 20000. - Michael S. Branicky, Nov 15 2024

Links

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

Example

1, 2 and 6 are terms since 1+1, 22+1 and 666666+1 are prime numbers.

Crossrefs

Cf. A000461.

Sequence in context: A140258 A071093 A114045 * A357193 A355556 A162146

Adjacent sequences: A116896 A116897 A116898 * A116900 A116901 A116902

Keyword

base,hard,more,nonn

Author

Giovanni Resta, Mar 07 2006

Status

approved