This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A165572 #11 Jul 22 2025 13:11:06
%S A165572 3,5,11,31,37,47,157,571,911,1021,1487,2351,3571,24709,25463,69247,
%T A165572 80803,216103,290141,465277,822691,1485373,1785473,3206767,14855327,
%U A165572 27439609,28075231,84468479,107765599,161223523,218252393,788298307,1018470703,1527131129,2472296341
%N A165572 Greater prime factor of successively better golden semiprimes.
%C A165572 See A165569 and A165570 for the definition. Probably a subset of A108542.
%H A165572 Amiram Eldar, <a href="/A165572/b165572.txt">Table of n, a(n) for n = 1..48</a>
%F A165572 a(n) = A108539(A165569(n)).
%F A165572 a(n) = A165570(n)/A165571(n).
%t A165572 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 *)
%Y A165572 Cf. A108539, A165569, A165570, A165571.
%K A165572 nonn
%O A165572 1,1
%A A165572 _Antti Karttunen_, Sep 22 2009
%E A165572 a(16)-a(23) from _Donovan Johnson_, May 13 2010
%E A165572 a(24)-a(35) from _Amiram Eldar_, Nov 28 2019