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 A089682 Primes of the form 3*m^2 - 1. 7
 2, 11, 47, 107, 191, 431, 587, 971, 1451, 2027, 2351, 2699, 3467, 4799, 5807, 6911, 7499, 8111, 8747, 10091, 10799, 14699, 15551, 16427, 17327, 18251, 25391, 27647, 36299, 41771, 44651, 55487, 57131, 62207, 67499, 71147, 74891, 80687, 92927 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 431 and 27647 also have the form 2*m^3-1 (431 = 3*12^2-1 = 2*6^3-1 and 27647 = 3*96^2-1 = 2*24^3-1). [Howard Berman (howard_berman(AT)hotmail.com), May 09 2009] Or, primes p such that 3*(p+1) is a square. [Vincenzo Librandi, Nov 18 2010] Obviously m must be either 1 or an even number. So this consists of 1 together with primes of the form 12*u^2 - 1. - N. J. A. Sloane, Aug 09 2019 REFERENCES M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988 Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 MATHEMATICA Select[Table[3 n^2 - 1, {n, 0, 2000}], PrimeQ] (* Vincenzo Librandi, Jul 16 2012 *) PROG (Magma) [a: n in [0..200] | IsPrime(a) where a is 3*n^2-1]; // Vincenzo Librandi, Jul 16 2012 CROSSREFS Primes in A080663. Sequence in context: A229019 A142346 A106980 * A211671 A198693 A178710 Adjacent sequences: A089679 A089680 A089681 * A089683 A089684 A089685 KEYWORD nonn,easy AUTHOR Giovanni Teofilatto, Jan 05 2004 EXTENSIONS More terms from Rick L. Shepherd, May 18 2005 STATUS approved

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Last modified December 11 07:17 EST 2023. Contains 367717 sequences. (Running on oeis4.)