A113525 Semiprimes in A056107.

4, 49, 301, 589, 973, 2353, 2701, 3073, 4333, 5293, 5809, 6349, 6913, 7501, 8749, 9409, 10801, 11533, 13069, 14701, 15553, 16429, 23233, 24301, 25393, 27649, 30001

Offset: 1

Author

Jonathan Vos Post, Jan 12 2006

Keywords

• easy
• nonn

Comments

Intersection of A056107 and A001358.

Examples

			a(1) = 4 because A056107(1) = 3*1^2 + 1 = 4 = 2^2 is semiprime.
a(16) = 9409 because A056107(56) = 3*56^2 + 1 = 9409 = 97^2 is semiprime.
a(27) = 30001 because A056107(100) = 3*100^2 + 1 = 30001 = 19 * 1579 is semiprime.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001358, A056107.

Cf. A113519, A113524, A113527, A113528, A113530.

Programs

Mathematica

Select[Array[3 #^2 + 1 &, 100], PrimeOmega[#] == 2 &] (* Michael De Vlieger, Mar 17 2021 *)