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 A088485 Numbers n such that n^2 + n - 1 and n^2 + n + 1 are twin primes. 19
 2, 3, 5, 6, 8, 15, 20, 21, 24, 38, 41, 50, 54, 59, 66, 89, 101, 131, 138, 141, 153, 155, 164, 176, 188, 203, 206, 209, 215, 218, 231, 236, 246, 288, 290, 309, 314, 351, 378, 395, 405, 453, 455, 456, 495, 500, 518, 530, 551, 560, 624, 644, 668, 686, 720, 728, 743, 761, 798, 825, 890, 915, 950, 974, 981 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A265006 gives these primes. - Derek Orr, Dec 24 2015 LINKS Pierre CAMI, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe) EXAMPLE 20*20 + 20 - 1 = 419, 419 and 421 twin primes, 20 is the 7th of the sequence MATHEMATICA Select[Range[500], PrimeQ[ #^2+#-1] && PrimeQ[ #^2+#+1] &] (* T. D. Noe, Jun 22 2004 *) Select[Range[1000], AllTrue[#^2+#+{1, -1}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 12 2017 *) PROG (PARI) for(n=1, 10^3, if(isprime(n^2+n-1)&&isprime(n^2+n+1), print1(n, ", "))) \\ Derek Orr, Dec 24 2015 (Magma) [n: n in [1..2*10^3] |IsPrime(n^2+n-1) and IsPrime(n^2+n+1)]; // Vincenzo Librandi, Dec 26 2015 CROSSREFS Cf. A088483, A265006. Sequence in context: A239263 A216293 A088497 * A194626 A275323 A128994 Adjacent sequences: A088482 A088483 A088484 * A088486 A088487 A088488 KEYWORD nonn,easy AUTHOR Pierre CAMI, Nov 09 2003 EXTENSIONS Corrected description from T. D. Noe, Jun 22 2004 STATUS approved

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Last modified December 8 13:46 EST 2023. Contains 367679 sequences. (Running on oeis4.)