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 A226925 Values of n such that L(5) and N(5) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n. 1
 1, 3, -17, 19, -39, 39, -45, -65, 73, -95, -101, 129, -137, -153, 165, 207, -233, 295, -297, -323, 339, -389, 417, 463, 481, -521, -569, -597, -617, -687, 729, 753, -765, 801, -855, -1005, -1025, 1081, 1093, -1115, 1179, -1229, 1231, -1235, -1245, -1275, -1287, 1293, -1319, 1345, -1389, 1417, -1437, 1495, -1521, 1569, 1749, 1755, -1767, -1793, 1807, 1819, -1917 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..295 Eric L. F. Roettger, A cubic extension of the Lucas functions, Thesis, Dept. of Mathematics and Statistics, Univ. of Calgary, 2009. See page 195. MATHEMATICA k = 5; (* adjust for related sequences *) fL[n_] := (n^2 + n + 1)*2^(2*k) + (2*n + 1)*2^k + 1; fN[n_] := (n^2 + n + 1)*2^k + n; nn = 2000; A = {}; For[n = -nn, n <= nn, n++, If[PrimeQ[fL[n]] && PrimeQ[fN[n]], AppendTo[A, n]]]; cmpfunc[x_, y_] := If[x == y, Return[True], ax = Abs[x]; ay = Abs[y]; If[ax == ay, Return[x < y], Return[ ax < ay]]]; Sort[A, cmpfunc] (* Jean-François Alcover, Jul 17 2013, translated and adapted from Joerg Arndt's Pari program in A226921 *) CROSSREFS Cf. A226921 - A226929, A227448, A227449, A227515 - A227523. Sequence in context: A019342 A029473 A103088 * A259772 A082387 A032923 Adjacent sequences:  A226922 A226923 A226924 * A226926 A226927 A226928 KEYWORD sign AUTHOR N. J. A. Sloane, Jul 12 2013 EXTENSIONS More terms from Vincenzo Librandi, Jul 13 2013 First term added from Bruno Berselli at the suggestion of Vincenzo Librandi, Jul 15 2013 STATUS approved

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Last modified January 19 09:35 EST 2020. Contains 331048 sequences. (Running on oeis4.)