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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.
2
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
CROSSREFS
Sequence in context: A072849 A287930 A287799 * A100986 A213141 A075732
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