A075611 a(1) = 1, a(n) = smallest number > a(n-1) such that concatenation a(k) a(n) is prime for all k = 1 to n-1. Stop if no such number exists.

1, 3, 7, 73, 433, 607, 13381, 37279, 4800307, 1281054613, 63338216281

Offset

1,2

Comments

The sequence is probably finite.

Links

Table of n, a(n) for n=1..11.

Example

a(5)=433 since 1433, 3433, 7433 and 73433 are all primes and for every 73<x<433, at least one of 1x, 3x, 7x, 73x is not prime.

Crossrefs

Sequence in context: A354893 A342546 A088647 * A191485 A119572 A362651

Adjacent sequences: A075608 A075609 A075610 * A075612 A075613 A075614

Keyword

base,more,nonn

Author

Amarnath Murthy, Sep 28 2002

Extensions

Corrected and extended by Giovanni Resta, Jun 18 2003

a(11) from Michael S. Branicky, Jul 31 2024

Status

approved