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A083351
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Numbers n such that 5*7^n + 2 is prime.
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0
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0, 1, 4, 9, 12, 25, 132, 192, 459, 10377, 45130, 63589, 83265
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OFFSET
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1,3
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COMMENTS
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Values corresponding to 9, 12, 25, 132, 192 and 459 (389 digits) have been certified prime with Primo. There are no other terms <= 4000.
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LINKS
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EXAMPLE
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7, 37, 12007, 201768037, 69206436007, 6705343098319824504037
are 5*7^0 + 2, 5*7^1 + 2, 5*7^4 + 2, 5*7^9 + 2, 5*7^12 + 2, 5*7^25 + 2,
respectively. 5*7^132 + 2 has 113 digits.
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PROG
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(PARI) for(n=0, 4000, if(isprime(5*7^n+2), print1(n, ", ")))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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