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

1,2

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

Links

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

Crossrefs

Sequence in context: A072849 A287930 A287799 * A100986 A213141 A075732

Adjacent sequences: A089320 A089321 A089322 * A089324 A089325 A089326

Keyword

base,hard,nonn

Author

Amarnath Murthy, Nov 03 2003

Extensions

More terms from Ray G. Opao, Jan 13 2005

3 more terms from David Wasserman, Sep 13 2005

Status

approved