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A285938
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Numbers k such that (19*10^k + 149)/3 is prime.
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0
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1, 2, 5, 7, 8, 11, 16, 29, 73, 169, 212, 227, 262, 547, 863, 1325, 2035, 4808, 8405, 13612, 16687, 19456, 122501
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OFFSET
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1,2
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COMMENTS
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For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 3 followed by the digits 83 is prime (see Example section).
a(24) > 2*10^5.
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LINKS
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Table of n, a(n) for n=1..23.
Makoto Kamada, Factorization of near-repdigit-related numbers.
Makoto Kamada, Search for 63w83.
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EXAMPLE
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5 is in this sequence because (19*10^5+149)/3 = 633383 is prime.
Initial terms and primes associated:
a(1) = 1, 113;
a(2) = 2, 683;
a(3) = 5, 633383;
a(4) = 7, 63333383;
a(5) = 8, 633333383; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(19*10^# + 149)/3] &]
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CROSSREFS
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Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
Sequence in context: A032724 A153308 A216565 * A325441 A192111 A294635
Adjacent sequences: A285935 A285936 A285937 * A285939 A285940 A285941
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KEYWORD
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nonn,more,hard
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AUTHOR
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Robert Price, Apr 29 2017
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EXTENSIONS
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a(23) from Robert Price, May 17 2019
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STATUS
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approved
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