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A169583
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n-th prime*8-7 is the square of a prime.
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1
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1, 4, 12, 19, 47, 59, 115, 167, 217, 251, 306, 348, 414, 618, 630, 662, 809, 1077, 1138, 1218, 1670, 1876, 2272, 2680, 2869, 3402, 3633, 4242, 4353, 4661, 5255, 6463, 6596, 6986, 8543, 8870, 8992, 9340, 9444, 10265, 11544, 11921, 12449, 13887, 14031
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OFFSET
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1,2
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LINKS
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EXAMPLE
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1 is in the sequence because 1st prime*8-7=(2nd prime)^2;
4 is in the sequence because 4th prime*8-7=(4th prime)^2;
12 is in the sequence because 12th prime*8-7=(7th prime)^2.
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MATHEMATICA
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Select[Range[15000], PrimeQ[Sqrt[8Prime[#]-7]]&] (* Harvey P. Dale, Nov 10 2017 *)
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PROG
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(PARI) isok(n) = issquare(sq=prime(n)*8-7) && isprime(sqrtint(sq)); \\ Michel Marcus, Apr 15 2014
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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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Corrected (1077 inserted) and extended by R. J. Mathar, Jun 04 2010
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STATUS
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approved
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