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A154939
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Primes p such that (p-1)*(p+1)-+p are primes.
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9
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3, 5, 11, 31, 101, 131, 149, 181, 241, 331, 419, 449, 709, 1051, 1061, 1171, 1409, 1549, 1579, 1699, 1759, 1831, 2069, 3229, 3449, 3761, 3911, 4159, 4951, 5821, 6029, 6481, 6661, 6679, 6899, 7079, 7151, 7229, 7369, 8101, 8219, 8629, 8861, 9091, 9161, 9521
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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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EXAMPLE
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2*4=8-+3 -> primes, 4*6=24-+5 -> primes,...
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MATHEMATICA
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lst={}; Do[p=Prime[n]; If[PrimeQ[(p-1)*(p+1)-p]&&PrimeQ[(p-1)*(p+1)+p], AppendTo[lst, p]], {n, 7!}]; lst
Select[Prime[Range[1500]], And@@PrimeQ/@{#^2 - # - 1, #^2 + # - 1} &] (* Vincenzo Librandi, Jul 10 2016 *)
Select[Prime[Range[1500]], AllTrue[(#-1)(#+1)+{#, -#}, PrimeQ]&] (* Harvey P. Dale, Sep 21 2023 *)
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PROG
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(Magma) [p: p in PrimesUpTo(10000) | IsPrime(p^2+p-1) and IsPrime(p^2-p-1)]; // Vincenzo Librandi, Jul 10 2016
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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