A248649 Numbers n that are the product of three distinct primes such that x^2+y^2 = n has integer solutions.

130, 170, 290, 370, 410, 442, 530, 610, 730, 754, 890, 962, 970, 986, 1010, 1066, 1090, 1105, 1130, 1258, 1370, 1378, 1394, 1490, 1570, 1586, 1730, 1802, 1810, 1885, 1898, 1930, 1970, 2074, 2146, 2290, 2314, 2330, 2378, 2405, 2410, 2465, 2482, 2522, 2570

Offset: 1

Author

Colin Barker, Oct 12 2014

Keywords

• nonn

Comments

Union of 2*A131574 and A264498. - Ray Chandler, Dec 09 2019

Examples

			130 is in the sequence because 130 = 2*5*13, and x^2+y^2=130 has integer solutions (x,y) = (3,11) and (7,9).
1105 is in the sequence because x^2 + y^2 = 1105 = 5*13*17 has solutions (x,y) = (4,33), (9,32), (12,31) and (23,24).
		

Links

• Ray Chandler, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A131574, A264498, A248712.

Programs

Mathematica

Select[Range[3000],PrimeNu[#]==PrimeOmega[#]==3&&FindInstance[x^2+y^2==#,{x,y},Integers]!={}&] (* Harvey P. Dale, Dec 16 2023 *)