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A272622
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Numbers k such that 9*10^k + 19 is prime.
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0
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1, 2, 4, 5, 10, 14, 25, 34, 40, 63, 74, 129, 149, 345, 370, 425, 477, 627, 951, 1610, 2564, 2689, 4227, 7300, 7444, 8360, 16541, 21187, 25685, 31803, 89858, 92821
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OFFSET
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1,2
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COMMENTS
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For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 0 followed by the digits 19 is prime (see Example section).
a(33) > 3*10^5.
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LINKS
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EXAMPLE
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4 is in this sequence because 9*10^4+19 = 90019 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 2, 919;
a(3) = 4, 90019;
a(4) = 5, 900019;
a(5) = 10, 90000000019, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[9*10^# + 19] &]
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PROG
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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