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 A038874 Primes p such that 3 is a square mod p. 11
 2, 3, 11, 13, 23, 37, 47, 59, 61, 71, 73, 83, 97, 107, 109, 131, 157, 167, 179, 181, 191, 193, 227, 229, 239, 241, 251, 263, 277, 311, 313, 337, 347, 349, 359, 373, 383, 397, 409, 419, 421, 431, 433, 443, 457, 467, 479, 491, 503, 541, 563, 577, 587, 599, 601 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also primes congruent to {1, 2, 3, 11} mod 12. The subsequence p = 1 (mod 4) corresponds to A068228 and only these entries of a(n) are squares mod 3 (from the quadratic reciprocity law). - Lekraj Beedassy, Jul 21 2004 Largest prime factors of n^2 - 3. - Vladimir Joseph Stephan Orlovsky, Aug 12 2009 Aside from 2 and 3, primes p such that Legendre(3, p) = 1. Bolker asserts there are infinitely many of these primes. - Alonso del Arte, Nov 25 2015 The associated bases of the squares are 1, 0, 5, 4, 7, 15, 12, 11, 8, 28, 21, 13...: 1^2 = 3 -1*2, 0^2 = 3-1*3, 5^2 = 3+ 2*11, 4^2 = 3+1*13, 7^2 = 3+2*23, 15^2 = 3+6*37, 12^2 = 3+3*47,... - R. J. Mathar, Feb 23 2017 REFERENCES Ethan D. Bolker, Elementary Number Theory: An Algebraic Approach. Mineola, New York: Dover Publications (1969, reprinted 2007): p. 74, Theorem 25.3. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Tamara M. Lavshuk, Regular polygons and polyhedra over finite field, Mathematical Notes of NEFU, Vol 22 No 4 (2015). Mentions this sequence. FORMULA a(n) ~ 2n log n. - Charles R Greathouse IV, Nov 29 2016 EXAMPLE 11 is in the sequence since the equation x^2 - 11y = 3 has solutions, such as x = 5, y = 2. 13 is in the sequence since the equation x^2 - 13y = 3 has solutions, such as x = 4, y = 1. 17 is not in the sequence because x^2 - 17y = 3 has no solutions in integers; Legendre(3, 17) = -1. MAPLE select(isprime, [2, 3, seq(seq(6+s+12*i, s=[-5, 5]), i=0..1000)]); # Robert Israel, Dec 23 2015 MATHEMATICA Select[Prime[Range[250]], MemberQ[{1, 2, 3, 11}, Mod[#, 12]] &] (* Vincenzo Librandi, Aug 08 2012 *) Select[Flatten[Join[{2, 3}, Table[{12n - 1, 12n + 1}, {n, 50}]]], PrimeQ] (* Alonso del Arte, Nov 25 2015 *) PROG (Magma) [p: p in PrimesUpTo(1200) | p mod 12 in [1, 2, 3, 11]]; // Vincenzo Librandi, Aug 08 2012 (PARI) forprime(p=2, 1e3, if(issquare(Mod(3, p)), print1(p , ", "))) \\ Altug Alkan, Dec 04 2015 CROSSREFS Cf. A002313, A033203, A038873, A045331, A057125. If the first two terms are omitted we get A097933. A040101 is another sequence. Sequence in context: A090707 A062350 A163498 * A164624 A215819 A040101 Adjacent sequences: A038871 A038872 A038873 * A038875 A038876 A038877 KEYWORD nonn,easy AUTHOR N. J. A. Sloane EXTENSIONS More terms from Henry Bottomley, Aug 10 2000 STATUS approved

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Last modified June 17 15:57 EDT 2024. Contains 373463 sequences. (Running on oeis4.)