%I #9 Nov 28 2019 06:13:27

%S 2,3,7,11,19,23,29,37,41,67,79,97,101,103,107,131,149,163,167,181,193,

%T 227,241,271,277,283,311,353,367,379,383,397,409,419,433,449,457,487,

%U 509,563,607,613,631,661,719,733,761,797,853,883,919,941,971,997,1031

%N Lesser prime factor of n-th golden semiprime.

%C abs(phi*a(n) - A108542(n)) < 1, where phi = golden ratio = (1+sqrt(5))/2.

%H Amiram Eldar, <a href="/A108541/b108541.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A108540(n)/A108542(n).

%t 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 *)

%Y Cf. A001622, A084126, A108539, A108540, A108542, A108543, A108544.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jun 09 2005