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A165572 Greater prime factor of successively better golden semiprimes. 5
3, 5, 11, 31, 37, 47, 157, 571, 911, 1021, 1487, 2351, 3571, 24709, 25463, 69247, 80803, 216103, 290141, 465277, 822691, 1485373, 1785473, 3206767, 14855327, 27439609, 28075231, 84468479, 107765599, 161223523, 218252393, 788298307, 1018470703, 1527131129, 2472296341 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A165569 and A165570 for the definition. Probably a subset of A108542.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..48

FORMULA

a(n) = A108539(A165569(n)).

a(n) = A165570(n)/A165571(n).

MATHEMATICA

f[p_] := Module[{x = GoldenRatio * p, p1, p2}, p1 = NextPrime[x, -1]; p2 = NextPrime[p1]; If[p2 - x > x - p1, p1, p2]]; seq={}; dm = 1; p1 = 1; Do[p1 = NextPrime[p1]; k++; p2 = f[p1]; d = Abs[p2/p1 - GoldenRatio]; If[d < dm, dm = d; AppendTo[seq, p2]], {10^4}]; seq  (* Amiram Eldar, Nov 28 2019 *)

CROSSREFS

Cf. A108539, A165569, A165570, A165571.

Sequence in context: A214089 A108259 A093933 * A246901 A236568 A095184

Adjacent sequences:  A165569 A165570 A165571 * A165573 A165574 A165575

KEYWORD

nonn,more

AUTHOR

Antti Karttunen, Sep 22 2009

EXTENSIONS

a(16)-a(23) from Donovan Johnson, May 13 2010

a(24)-a(35) from Amiram Eldar, Nov 28 2019

STATUS

approved

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Last modified August 5 20:11 EDT 2021. Contains 346488 sequences. (Running on oeis4.)