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A276118
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Numbers n such that 42 * 10^n + 1 is prime.
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0
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0, 1, 2, 4, 13, 19, 39, 62, 76, 79, 109, 184, 222, 265, 370, 626, 670, 679, 763, 1950, 2174, 3379, 7369, 9087, 34990, 47535, 97970
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OFFSET
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1,3
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COMMENTS
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For n > 0, numbers such that the digits 42 followed by n - 1 occurrences of the digit 0 followed by the digit 1 is prime (see the Example section).
a(28) > 10^5.
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LINKS
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EXAMPLE
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4 is in this sequence because 42*10^4+1 = 420001 is prime.
Initial terms and primes associated:
a(1) = 0, 43;
a(2) = 1, 421;
a(3) = 2, 4201;
a(4) = 4, 420001;
a(5) = 13, 420000000000001, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[42 * 10^# + 1] &]
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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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