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A273097
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Numbers k such that 4*10^k + 87 is prime.
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0
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1, 2, 4, 5, 13, 25, 27, 32, 37, 38, 40, 45, 57, 80, 91, 151, 214, 441, 644, 764, 797, 1222, 2329, 2931, 4324, 21794, 22396, 24041, 46420, 51489, 55165, 126625
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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 87 is prime (see Example section).
a(33) > 3*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 + 87 = 40087 is prime.
Initial terms and primes associated:
a(1) = 1, 127:
a(2) = 2, 487;
a(3) = 4, 40087;
a(4) = 5, 400087;
a(5) = 13, 40000000000087, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[4*10^# + 87] &]
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PROG
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CROSSREFS
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KEYWORD
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nonn,more,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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