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

Offset

1,2

Comments

The sequence is probably finite.

Links

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

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

Status

approved