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A087604
Smallest k such that n times concatenation of k with itself followed by a 3 is a prime, or 0 if no such number exists.
7
1, 1, 0, 1, 4, 0, 2, 1, 0, 1, 4, 0, 37, 7, 0, 17, 149, 0, 185, 7, 0, 73, 1, 0, 5, 47, 0, 38, 4, 0, 4, 133, 0, 52, 2, 0, 194, 46, 0, 37, 29, 0, 29, 25, 0, 19, 14, 0, 74, 8, 0, 19, 20, 0, 442, 83, 0, 358, 211, 0, 16, 298, 0, 260, 5, 0, 305, 71, 0, 8, 323, 0, 5, 109, 0, 8, 68, 0, 767, 367
OFFSET
1,5
COMMENTS
Trivially a(3n) = 0. Conjecture: no other term is zero.
Either a(13)=0 or a(13)>36. This sequence contains no positive multiples of 3. If a(m) is of the form bbb...b (repeated k times) then a(km) <= b. - Sam Alexander, Oct 20 2003
EXAMPLE
a(5) = 4 as 444443 is a prime. but 111113,222223,333333 are not.
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 18 2003
EXTENSIONS
More terms from Sam Alexander, Oct 20 2003
More terms from Ray G. Opao, Apr 15 2004
More terms from David Wasserman, Jun 16 2005
STATUS
approved