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A281829
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Numbers k such that 4*10^k + 93 is prime.
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0
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0, 3, 4, 5, 6, 16, 20, 21, 27, 29, 68, 81, 89, 100, 125, 388, 737, 869, 1398, 2614, 8111, 14777, 15696, 22299, 42423, 52272, 84346, 157150, 180360
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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 4 followed by k-2 occurrences of the digit 0 followed by the digits 93 is prime (see Example section).
a(30) > 2*10^5.
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LINKS
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EXAMPLE
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4 is in this sequence because 4*10^4 + 93 = 40093 is prime.
Initial terms and associated primes:
a(1) = 0, 97;
a(2) = 3, 4093;
a(3) = 4, 40093;
a(4) = 5, 400093;
a(5) = 6, 4000093; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[4*10^# + 93] &]
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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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