%I #19 May 26 2021 02:53:37
%S 441,693,1089,1197,1449,1617,1881,1953,2277,2541,2709,2793,2961,3069,
%T 3249,3381,3717,3933,4221,4257,4473,4557,4653,4761,4977,5229,5301,
%U 5841,5929,6321,6417,6489,6633,6741,6897,6909,7029,7353,7581,7821,8001,8037,8217,8253
%N Numbers which are the product of two Sprimes (A057948) in exactly two ways.
%C First differs from A057950 at a(21)=4473, whereas A057950(21)=4389, which can be represented as the product of two Sprimes in exactly 3 ways.
%C There exist numbers which are the product of two Sprimes in exactly 1, 2, and 3 ways; however, it is unknown if any numbers exist which are the product of two Sprimes in exactly 4 ways.
%H Zachary DeStefano, <a href="/A343827/b343827.txt">Table of n, a(n) for n = 1..2484</a>
%F a(n) == 1 (mod 4).  _Hugo Pfoertner_, May 01 2021
%e 1449=9*161=21*69 which are all Sprimes (A057948), and admits no other Sprime factorizations.
%o (PARI) \\ uses is(n) from A057948
%o isok(n) = sumdiv(n, d, (d<=n/d) && is(d) && is(n/d)) == 2; \\ _Michel Marcus_, May 01 2021
%Y Cf. A054520, A057948, A057949, A057950.
%Y Exactly one way: A343826. Exactly three ways: A343828.
%K nonn
%O 1,1
%A _Zachary DeStefano_, Apr 30 2021
