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 A108701 Values of n such that n^2-2 and n^2+2 are both prime. 16
 3, 9, 15, 21, 33, 117, 237, 273, 303, 309, 387, 429, 441, 447, 513, 561, 573, 609, 807, 897, 1035, 1071, 1113, 1143, 1233, 1239, 1311, 1563, 1611, 1617, 1737, 1749, 1827, 1839, 1953, 2133, 2211, 2283, 2589, 2715, 2721, 2955, 3081, 3093, 3453, 3549, 3555, 3621, 3723, 3807 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Since x^2 + 2 is divisible by 3 unless x is divisible by 3, all elements are 3 mod 6. Intersection of A067201 and A028870. - Robert Israel, Sep 11 2014 REFERENCES David Wells, Prime Numbers, John Wiley and Sons, 2005, p. 219 (article:'Siamese primes') LINKS Nathaniel Johnston, Table of n, a(n) for n = 1..8750 Raymond A. Beauregard and E. R. Suryanarayan, Square-plus-two primes, Mathematical Gazette 85(502) 90-1. EXAMPLE 21 is on the list since 21^2 - 2 = 439 and 21^2 + 2 = 443 are primes. MAPLE select(n -> isprime(n^2-2) and isprime(n^2+2), [seq(6*i+3, i=0..1000)]); # Robert Israel, Sep 11 2014 MATHEMATICA Select[Range[5000], PrimeQ[#^2 - 2] && PrimeQ[#^2 + 2] &] (* Alonso del Arte, Sep 11 2014 *) PROG (MAGMA) [n: n in [3..3600 by 6] | IsPrime(n^2-2) and IsPrime(n^2+2)];  // Bruno Berselli, Apr 15 2011 (PARI) is(n)=isprime(n^2-2)&&isprime(n^2+2) \\ Charles R Greathouse IV, Jul 02 2013 CROSSREFS Subsequence of A016945. Cf. A016945, A028870, A028873, A038599, A067201, A153974. Sequence in context: A276967 A114271 A137164 * A064539 A029482 A174786 Adjacent sequences:  A108698 A108699 A108700 * A108702 A108703 A108704 KEYWORD nonn,easy AUTHOR John L. Drost, Jun 19 2005 EXTENSIONS Terms corrected by Charles R Greathouse IV, Sep 11 2014 STATUS approved

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Last modified September 18 10:13 EDT 2021. Contains 347518 sequences. (Running on oeis4.)