A089323 Smallest k such that concatenation of r*k and 1 is a prime for all r = 1 to n, or smallest k such that 10*r*k +1 is a prime for all r = 1 to n.

1, 3, 21, 33, 1083, 2541, 51282, 51282, 1296060612, 43449172767, 189324538095

Offset: 1

Author

Amarnath Murthy, Nov 03 2003

Keywords

• base
• hard
• nonn

Comments

The primes arising in triangular form are

11

31 61

211 421 631

331 661 991 1321

...

Next term is > 1.38*10^12. - David Wasserman, Sep 13 2005

Extensions

More terms from Ray G. Opao, Jan 13 2005

3 more terms from David Wasserman, Sep 13 2005