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 A089241 Even numbers k such that k/2 - 1 is prime. 5
 6, 8, 12, 16, 24, 28, 36, 40, 48, 60, 64, 76, 84, 88, 96, 108, 120, 124, 136, 144, 148, 160, 168, 180, 196, 204, 208, 216, 220, 228, 256, 264, 276, 280, 300, 304, 316, 328, 336, 348, 360, 364, 384, 388, 396, 400, 424, 448, 456, 460, 468, 480, 484 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 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..5000 FORMULA a(n) = 2*prime(n) + 2. - Alonso del Arte, Mar 02 2017 MATHEMATICA 2Prime[Range[100]] + 2 (* Alonso del Arte, Mar 06 2017 *) PROG (PARI) a(n)=2*prime(n) + 2 \\ Charles R Greathouse IV, Mar 06 2017 (MAGMA) [2*NthPrime(n)+2: n in [1..60]]; // Vincenzo Librandi, Jan 09 2018 CROSSREFS a(n) = A072055(n) + 1. a(n) = A029933(A000040(n)). Sequence in context: A115166 A050992 A090259 * A280270 A315862 A315863 Adjacent sequences:  A089238 A089239 A089240 * A089242 A089243 A089244 KEYWORD easy,nonn AUTHOR Giovanni Teofilatto, Dec 22 2003 EXTENSIONS Corrected (62 replaced by 64, 202 replaced by 204, 314 by 316, 386 by 388) by R. J. Mathar, Apr 22 2010 Offset corrected by Arkadiusz Wesolowski, Aug 09 2011 STATUS approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)