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A108541
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Lesser prime factor of n-th golden semiprime.
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10
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2, 3, 7, 11, 19, 23, 29, 37, 41, 67, 79, 97, 101, 103, 107, 131, 149, 163, 167, 181, 193, 227, 241, 271, 277, 283, 311, 353, 367, 379, 383, 397, 409, 419, 433, 449, 457, 487, 509, 563, 607, 613, 631, 661, 719, 733, 761, 797, 853, 883, 919, 941, 971, 997, 1031
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OFFSET
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1,1
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COMMENTS
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abs(phi*a(n) - A108542(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)/A108542(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]; If[f[p] > 0, AppendTo[seq, p]], {200}]; seq (* Amiram Eldar, Nov 28 2019 *)
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CROSSREFS
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Cf. A001622, A084126, A108539, A108540, A108542, A108543, A108544.
Sequence in context: A090666 A140409 A201011 * A038937 A092940 A045326
Adjacent sequences: A108538 A108539 A108540 * A108542 A108543 A108544
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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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