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 A056905 Primes of the form k^2 + 5. 10
 5, 41, 149, 1301, 2309, 5189, 6089, 9221, 13001, 15881, 26249, 28229, 39209, 41621, 60521, 66569, 86441, 112901, 116969, 138389, 171401, 186629, 207941, 213449, 242069, 254021, 266261, 285161, 304709, 331781, 345749, 352841, 389381, 443561 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Except for a(0), a(n) mod 180 = 41 or 149 since k must be a multiple of 6 without being a multiple of 30 for k^2+5 to be prime. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1800 Eric Weisstein's World of Mathematics, Near-Square Prime FORMULA a(n) = 36 * A056906(n) + 5. EXAMPLE a(2)=149 since 12^2 + 5 = 149, which is prime. MATHEMATICA Select[Table[n^2+5, {n, 0, 7000}], PrimeQ] (* Vincenzo Librandi, Nov 30 2011 *) PROG (MAGMA) [a: n in [0..700] | IsPrime(a) where a is n^2+5]; // Vincenzo Librandi, Nov 30 2011 (PARI) is(n) = ispseudoprime(n) && issquare(n-5) \\ Felix FrÃ¶hlich, May 25 2018 CROSSREFS Cf. A002496, A056899, A049423, A005473. Sequence in context: A337393 A262340 A128347 * A105412 A271017 A270674 Adjacent sequences:  A056902 A056903 A056904 * A056906 A056907 A056908 KEYWORD nonn,easy AUTHOR Henry Bottomley, Jul 07 2000 STATUS approved

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Last modified October 1 00:54 EDT 2020. Contains 337440 sequences. (Running on oeis4.)