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 A031368 a(n) = prime(2n-1). 14
 2, 5, 11, 17, 23, 31, 41, 47, 59, 67, 73, 83, 97, 103, 109, 127, 137, 149, 157, 167, 179, 191, 197, 211, 227, 233, 241, 257, 269, 277, 283, 307, 313, 331, 347, 353, 367, 379, 389, 401, 419, 431, 439, 449, 461, 467, 487, 499, 509, 523, 547, 563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Appeared as a puzzle in "Stickelers", a nationally distributed feature, by Terry Stickels, Sep 28 2006. - Franklin T. Adams-Watters, Sep 28 2006 Also every second prime starting with 2. - Cino Hilliard, Dec 02 2007 Central terms of the triangle in A005145. - Reinhard Zumkeller, Aug 05 2009 a(n) = A219603(n) / A000040(n). - Reinhard Zumkeller, Nov 25 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 MAPLE A031368 := n->ithprime(2*n-1): seq(A031368(n), n=1..100); MATHEMATICA Table[ Prime[ 2n -1], {n, 52}] (* Robert G. Wilson v, Dec 01 2013 *) PROG (MAGMA) [ NthPrime(2*n-1): n in [1..1000] ]; // Vincenzo Librandi, Apr 11 2011 (Haskell) a031368 = a000040 . ((subtract 1) . (* 2)) a031368_list = map a000040 [1, 3 ..]  -- Reinhard Zumkeller, Nov 25 2012 CROSSREFS Cf. A000040, A031215. Cf. A005408. Sequence in context: A003627 A103203 A105875 * A020613 A135478 A019381 Adjacent sequences:  A031365 A031366 A031367 * A031369 A031370 A031371 KEYWORD nonn AUTHOR STATUS approved

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