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Search: id:A118941
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| A118941 |
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Primes p such that (p^2-5)/4 is prime. |
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4
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| 5, 7, 11, 13, 17, 19, 23, 31, 41, 43, 53, 61, 71, 79, 83, 89, 97, 101, 107, 109, 113, 131, 137, 167, 173, 179, 193, 229, 241, 251, 263, 269, 277, 281, 283, 307, 311, 317, 349, 353, 373, 383, 419, 431, 439, 461, 463, 467, 563, 571, 577, 593, 607, 613, 619, 647
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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For all primes q>2, we have q=4k+-1 for some k, which makes it easy to show that 4 divides q^2-5. Similar sequences, with p and (p^2+a)/b both prime, are A048161, A062324, A062326, A062718, A109953, A110589, A118915, A118918, A118939, A118940, and A118942.
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MATHEMATICA
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Select[Prime[Range[200]], PrimeQ[(#^2-5)/4]&]
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CROSSREFS
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Sequence in context: A020617 A020589 A101635 this_sequence A096547 A128824 A098420
Adjacent sequences: A118938 A118939 A118940 this_sequence A118942 A118943 A118944
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), May 06 2006
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