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A108542
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Greater prime factor of n-th golden semiprime.
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11
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3, 5, 11, 17, 31, 37, 47, 59, 67, 109, 127, 157, 163, 167, 173, 211, 241, 263, 271, 293, 313, 367, 389, 439, 449, 457, 503, 571, 593, 613, 619, 643, 661, 677, 701, 727, 739, 787, 823, 911, 983, 991, 1021, 1069, 1163, 1187, 1231, 1289, 1381, 1429, 1487, 1523
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OFFSET
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1,1
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COMMENTS
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abs(phi*A108541(n) - a(n)) < 1, where phi = golden ratio = (1+sqrt(5))/2.
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LINKS
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Amiram Eldar, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = A108540(n)/A108541(n).
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MATHEMATICA
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f[p_] := Module[{x = GoldenRatio * p}, p1 = NextPrime[x, -1]; p2 = NextPrime[p1]; q = If[x - p1 < p2 - x, p1, p2]; If[Abs[q - x] < 1, q, 0]]; seq = {}; p=1; Do[p = NextPrime[p]; q = f[p]; If[q > 0, AppendTo[seq, q]], {200}]; seq (* Amiram Eldar, Nov 28 2019 *)
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CROSSREFS
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Cf. A001622, A084127, A108540, A108541, A108543, A108544.
Subsequence of A108539.
Sequence in context: A309437 A309438 A309439 * A006450 A085918 A267094
Adjacent sequences: A108539 A108540 A108541 * A108543 A108544 A108545
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller, Jun 09 2005
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STATUS
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approved
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