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A226924 Values of n such that L(4) and N(4) 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
-5, 31, 223, 277, -323, 367, 415, 541, -593, -635, -785, 811, 877, -893, 937, 961, -995, -1019, -1055, 1063, 1081, 1117, -1205, 1315, -1349, -1523, -1583, -1607, 1837, 1915, -2117, -2369, 2515, -2777, -2915, -3287, 3301, -3329, 3343, 3391, -3743, -3959, 4027, -4163, -4457, -4553, 4573, 4651 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi and Joerg Arndt, Table of n, a(n) for n = 1..1000

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 = 4; (* 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 = 5000; 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-Fran├žois 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: A059035 A199877 A058309 * A192950 A001910 A052773

Adjacent sequences:  A226921 A226922 A226923 * A226925 A226926 A226927

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Jul 12 2013

EXTENSIONS

More terms from Vincenzo Librandi, Jul 13 2013

STATUS

approved

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Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)