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A226925
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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.
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1
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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
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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