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A276642
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Numbers k such that 3*10^k + 89 is prime.
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0
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2, 3, 4, 5, 6, 8, 10, 14, 15, 62, 98, 184, 190, 389, 430, 815, 918, 1124, 1284, 9544, 10068, 16514, 24756, 39880, 86478, 179138
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OFFSET
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1,1
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COMMENTS
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For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 89 is prime (see Example section).
a(27) > 2*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because 3*10^3 + 89 = 3089 is prime.
Initial terms and primes associated:
a(1) = 2, 389;
a(2) = 3, 3089;
a(3) = 4, 30089;
a(4) = 5, 300089;
a(5) = 6, 3000089; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[3*10^# + 89] &]
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PROG
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(PARI) isok(k) = ispseudoprime(3*10^k + 89); \\ Altug Alkan, Mar 30 2018
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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