A360740 Semiprimes of the form k^2 + 3.

4, 39, 259, 327, 403, 579, 679, 1027, 1159, 1299, 1603, 1939, 2119, 2307, 3139, 3603, 4359, 4627, 6087, 6403, 7747, 9607, 10003, 10407, 10819, 11667, 13459, 13927, 14403, 16387, 18499, 21907, 23107, 26899, 28903, 30279, 30979, 33127, 35347, 36103, 36867, 38419

Offset: 1

Author

Elmo R. Oliveira, Feb 18 2023

Keywords

• nonn
• easy

Comments

A242331 gives the corresponding values of k.

Examples

			259 is a term because 16^2 + 3 = 259 = 7*37.
		

Crossrefs

Cf. A001358, A085722, A117950, A144255, A242330, A242331.

Programs

Mathematica

Select[Range[0, 200]^2 + 3, PrimeOmega[#] == 2 &] (* Amiram Eldar, Feb 18 2023 *)

Formula

a(n) = A242331(n)^2 + 3.