A162731 a(n) is the n-th triprime (A014612) minus its central prime factor.

6, 10, 15, 18, 24, 26, 27, 39, 42, 42, 45, 50, 60, 63, 66, 65, 70, 74, 75, 90, 91, 96, 99, 100, 105, 111, 114, 114, 122, 120, 125, 135, 140, 146, 150, 147, 162, 160, 165, 168, 170, 171, 170, 175, 183, 186, 185, 190, 204, 210, 219, 225, 224, 234, 231, 231, 242, 238, 243, 250

Offset: 1

Author

Juri-Stepan Gerasimov, Jul 12 2009

Keywords

• nonn
• less

Examples

			a(1) =  6 = 2*2*2 - 2;
a(2) = 10 = 2*2*3 - 2;
a(3) = 15 = 2*3*3 - 3;
a(4) = 18 = 2*2*5 - 2;
a(5) = 24 = 3*3*3 - 3.
		

Crossrefs

Cf. A014612, A162361.

Formula

a(n) = A014612(n) - A162361(n).

Extensions

Definition reformulated, a(11), a(38) etc. corrected by R. J. Mathar, Jul 16 2009