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 A108542 Greater prime factor of n-th golden semiprime. 11
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS abs(phi*A108541(n) - a(n)) < 1, where phi = golden ratio = (1+sqrt(5))/2. LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A108540(n)/A108541(n). MATHEMATICA 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 *) CROSSREFS 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 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jun 09 2005 STATUS approved

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Last modified June 20 11:12 EDT 2024. Contains 373527 sequences. (Running on oeis4.)