%I #30 Dec 09 2019 12:57:58
%S 65,85,145,185,205,221,265,305,365,377,445,481,485,493,505,533,545,
%T 565,629,685,689,697,745,785,793,865,901,905,949,965,985,1037,1073,
%U 1145,1157,1165,1189,1205,1241,1261,1285,1313,1345,1385,1405,1417,1465,1469
%N Numbers n that are the product of two distinct odd primes and x^2 + y^2 = n has integer solutions.
%C The two primes are of the form 4*k + 1.
%H Ray Chandler, <a href="/A131574/b131574.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Colin Barker)
%e 65 is in the sequence because x^2 + y^2 = 65 = 5*13 has solutions (x,y) = (1,8), (4,7), (7,4) and (8,1).
%o (PARI)
%o dop(d, nmax) = {
%o my(L=List(), v=vector(d,m,1)~, f);
%o for(n=1, nmax,
%o f=factorint(n);
%o if(#f~==d && f[1,1]>2 && f[,2]==v && f[,1]%4==v, listput(L, n))
%o );
%o Vec(L)
%o }
%o dop(2, 3000) \\ _Colin Barker_, Nov 15 2015
%Y Cf. A000415, A121387, A248649, A248712, A264498, A264499
%K nonn
%O 1,1
%A _Colin Barker_, Aug 28 2007, corrected Aug 29 2007