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A271882
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Numbers n such that (10^n + 101)/3 is prime.
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0
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1, 2, 3, 6, 9, 12, 23, 39, 59, 168, 198, 203, 231, 449, 863, 920, 1064, 1484, 1674, 2018, 2943, 3123, 4073, 4122, 8360, 11774, 16031, 26507, 31146, 33170, 44952, 62402, 88020, 89687
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OFFSET
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1,2
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COMMENTS
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For n>1, numbers that begin with n-2 occurrences of the digit 3 followed by the digits 67 is prime (see Example section).
a(35) > 2*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because (10^3+101)/3 = 367 is prime.
Initial terms and primes associated:
a(1) = 1, 37;
a(2) = 2, 67;
a(3) = 3, 367;
a(4) = 6, 333367;
a(5) = 9, 333333367, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(10^#+101)/3] &]
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PROG
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(PARI) lista(nn) = for(n=1, nn, if(ispseudoprime((10^n+101)/3), print1(n, ", "))); \\ Altug Alkan, Apr 16 2016
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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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