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A089319
Smallest k > 1 such that k^n followed by digit 1 is a prime.
1
3, 2, 3, 3, 6, 2, 3, 6, 3, 11, 7, 2, 70, 2, 22, 18, 43, 3, 4, 649, 15, 3, 37, 2, 24, 13, 4, 8, 40, 77, 19, 22, 13, 24, 292, 48, 4, 2, 109, 792, 30, 4, 18, 5, 7, 90, 28, 138, 132, 891, 9, 25, 145, 2, 24, 9, 40, 28, 219, 165, 40, 41, 4, 13, 261, 24, 6, 30, 6, 154, 82, 22, 120, 2, 55
OFFSET
1,1
EXAMPLE
a(4) = 3 as concatenation of 3^4 and 1 = 811 is a prime. 161 is not a prime.
MATHEMATICA
Do[k = 2; While[ !PrimeQ[10*k^n + 1], k++ ]; Print[k], {n, 1, 30}] (* Ryan Propper, Jul 08 2005 *)
CROSSREFS
Cf. A089318.
Sequence in context: A058680 A070544 A087713 * A140396 A117231 A106151
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 03 2003
EXTENSIONS
Corrected and extended by Ryan Propper, Jul 08 2005
Further terms from David Wasserman, Sep 09 2005
STATUS
approved