A176406 Odd semiprimes minus 2.

7, 13, 19, 23, 31, 33, 37, 47, 49, 53, 55, 63, 67, 75, 83, 85, 89, 91, 93, 109, 113, 117, 119, 121, 127, 131, 139, 141, 143, 153, 157, 159, 167, 175, 181, 183, 185, 199, 201, 203, 207, 211, 213, 215, 217, 219, 233, 235, 245, 247, 251, 257, 263, 265, 285, 287

Offset: 1

Author

Juri-Stepan Gerasimov, Apr 16 2010

Keywords

• nonn

Crossrefs

Cf. A007921.

Programs

Maple

isA001358 := proc(n) numtheory[bigomega](n) = 2 ; end proc: for n from 1 to 400 by 2 do if isA001358(n+2) then printf("%d,",n) ; end if; end do: # R. J. Mathar, Apr 20 2010

Mathematica

Select[Range[9,301,2],PrimeOmega[#]==2&]-2 (* Harvey P. Dale, May 11 2018 *)

Formula

a(n) = A046315(n) - 2.

Extensions

Entries checked by R. J. Mathar, Apr 20 2010