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A068008
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Least number needed to be appended to n n's to make a prime.
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0
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2, 3, 3, 1, 9, 7, 29, 39, 3, 43, 39, 1, 23, 27, 97, 53, 91, 37, 251, 93, 93, 19, 97, 61, 293, 153, 163, 1, 297, 103, 323, 61, 127, 113, 31, 127, 353, 67, 841, 187, 9, 21, 179, 429, 127, 97, 3, 319, 11, 51, 39, 191, 33, 3, 41, 151, 39, 47, 169, 787, 401, 57, 441, 571
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Comment from Dan Dima, Jan 29 2007: This is not quite the "tail" of the numbers in A068120 because of the restriction that a(n) cannot begin with a zero.
For example a(25) = 153; 25252525252525252525252525252525252525252525252525153 is a prime, but it is greater than A068120(25) = 25252525252525252525252525252525252525252525252525061.
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EXAMPLE
| a(0) = 2 because 2 is prime, a(1) = 3 and not 1 because 13 is a prime whereas if 11 ( a prime) causes two ones in a row, a(2) = 3 because by appending to 22 a 3 we now have a prime, appending 1 produces 221 = 13*17.
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CROSSREFS
| Cf. A068120.
Sequence in context: A116155 A144149 A097005 * A123948 A188886 A131012
Adjacent sequences: A068005 A068006 A068007 * A068009 A068010 A068011
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KEYWORD
| nonn,base
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 22 2002
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