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Search: id:A075408
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| A075408 |
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Perfect powers pp such that pp+1 is prime. |
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+0
1
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| 1, 4, 16, 36, 100, 196, 256, 400, 576, 676, 1296, 1600, 2916, 3136, 4356, 5476, 7056, 8100, 8836, 12100, 13456, 14400, 15376, 15876, 16900, 17956, 21316, 22500, 24336, 25600, 28900, 30976, 32400, 33856, 41616, 42436, 44100, 50176, 52900, 55696
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Of 1110 pp's < 10^6, 112 are such that pp+1 is prime, and only seven are such that pp-1 is prime (see Mersenne primes (A000668)).
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MATHEMATICA
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pp = Join[ Select[ Range[56000], Apply[GCD, Last[ Transpose[ FactorInteger[ # ]]]] > 1 & ]]; Select[pp, PrimeQ[ # + 1] & ]
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CROSSREFS
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A002496(n) - 1.
Sequence in context: A085040 A030179 A005722 this_sequence A114268 A136404 A046952
Adjacent sequences: A075405 A075406 A075407 this_sequence A075409 A075410 A075411
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KEYWORD
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easy,nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Oct 11 2002
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2002 has merit. Thanx. Bob.
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