A175463 Numbers k such that 8*k + 5 is semiprime.

2, 8, 9, 10, 11, 16, 17, 25, 26, 27, 29, 31, 37, 38, 42, 45, 47, 51, 54, 55, 56, 58, 60, 61, 62, 64, 66, 70, 71, 72, 73, 74, 78, 83, 85, 89, 93, 97, 98, 101, 108, 111, 112, 114, 116, 118, 120, 121, 123, 129, 134, 137, 141, 142, 143, 144, 145, 148, 150, 156, 157, 160

Offset: 1

Author

Zak Seidov, May 24 2010

Keywords

• nonn

Crossrefs

Cf. A175461 Semiprimes of form 8*n+5.

Programs

Magma

IsSemiprime:=func< n | &+[ k[2]: k in Factorization(n) ] eq 2 >; [ n: n in [2..200] | IsSemiprime(8*n+5) ]; // Vincenzo Librandi, Dec 13 2010

Mathematica

Select[Range[200],PrimeOmega[8#+5]==2&] (* Harvey P. Dale, Aug 07 2011 *)

Formula

a(n) = (A175461(n) - 5)/8.