A113528 Semiprimes in A056109.

6, 34, 57, 86, 121, 209, 262, 321, 386, 706, 1241, 1366, 1497, 2582, 2761, 3334, 3746, 3961, 4881, 5377, 6166, 6722, 7009, 7601, 8857, 9862, 10562, 10921, 12417, 13201, 14422, 15697, 17026, 17481, 17942, 18409, 19361, 19846, 20337, 21337, 22361

Offset

1,1

Comments

Intersection of A056109 and A001358.

Links

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

Example

a(1) = 6 because A056109(1) = 3*1^2 + 2*1 + 1 = 6 = 2 * 3 is semiprime.

Mathematica

Select[Array[3 #^2 + 2 # + 1 &, 87], PrimeOmega[#] == 2 &] (* Michael De Vlieger, Mar 17 2021 *)

Crossrefs

Cf. A001358, A056109.

Cf. A113519, A113524, A113525, A113527, A113530.

Sequence in context: A011798 A222174 A044464 * A152528 A135733 A072312

Adjacent sequences: A113525 A113526 A113527 * A113529 A113530 A113531

Keyword

easy,nonn

Author

Jonathan Vos Post, Jan 12 2006

Status

approved