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A274336
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Numbers k such that (16*10^k - 91)/3 is prime.
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0
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1, 2, 3, 5, 16, 18, 22, 31, 40, 98, 99, 192, 233, 367, 501, 1102, 1381, 1416, 2018, 6156, 6860, 7377, 14004, 16634, 21422, 27654, 85473, 260256, 265052, 274251
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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 5 followed by k-1 occurrences of the digit 3 followed by the digits 03 is prime (see Example section).
a(31) > 3*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because (16*10^3 - 91)/3 = 5303 is prime.
Initial terms and associated primes:
a(1) = 1, 23;
a(2) = 2, 503;
a(3) = 3, 5303;
a(4) = 5, 533303;
a(5) = 16, 53333333333333303, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(16*10^# - 91)/3] &]
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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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EXTENSIONS
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STATUS
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approved
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