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A088502
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Numbers n such that (n^2 - 5)/4 is prime.
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4
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5, 7, 9, 11, 13, 17, 19, 21, 23, 27, 31, 33, 39, 41, 43, 49, 53, 57, 61, 63, 71, 77, 79, 83, 89, 91, 93, 97, 101, 107, 109, 111, 113, 119, 121, 129, 131, 133, 137, 141, 153, 167, 171, 173, 179, 187, 189, 193, 201, 203, 207, 229, 231, 241, 251, 253, 261, 263, 269
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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(23*23 - 5)/4 = 131, 131 is prime, 23 is the 9th n of the sequence.
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MATHEMATICA
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PROG
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(Magma) [n: n in [1..300 by 2] | IsPrime((n^2-5) div 4)]; // Vincenzo Librandi, Oct 06 2012
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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