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A086920
Smallest k such that n times concatenation of k with itself followed by a 1 is a prime, or 0 if no such number exists.
7
1, 3, 2, 3, 3, 3, 3, 30, 6, 4, 5, 5, 25, 42, 17, 19, 2, 1, 7, 6, 6, 1, 50, 29, 138, 153, 4, 45, 54, 7, 15, 9, 78, 147, 95, 58, 102, 18, 3, 115, 54, 6, 46, 9, 24, 64, 183, 120, 3, 33, 112, 46, 105, 4, 279, 122, 68, 75, 3, 22, 294, 56, 92, 76, 6, 19, 94, 71, 12, 75, 30, 16, 78, 320, 33
OFFSET
1,2
COMMENTS
Conjecture: no term is zero.
EXAMPLE
a(3) = 2 as 2221 is a prime. a(4) = 3 as 33331 is a prime but 11111 and 22221 are not.
a(8) = 30 and the prime arising is 30303030303030301.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 18 2003
EXTENSIONS
More terms from Ray G. Opao, Apr 15 2004
More terms from David Wasserman, Apr 12 2005
STATUS
approved