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A278470
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Numbers n such that 10^n - 201 is prime.
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2
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OFFSET
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1,1
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COMMENTS
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For n>2, numbers such that n-3 occurrences of the digit 9 followed by the digits 799 is prime.
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LINKS
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EXAMPLE
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13 is in this sequence because 10^13 - 201 = 9999999999799 is prime.
Initial terms and primes associated:
a(1) = 13, 9999999999799;
a(2) = 20, 99999999999999999799;
a(3) = 40, 9999999999999999999999999999999999999799; etc.
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MAPLE
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MATHEMATICA
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Select[Range[3, 2000], PrimeQ[10^# - 201] &]
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PROG
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(Magma) [n: n in [3..500] | IsPrime(10^n-201)];
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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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