A129928 - OEIS

%I #10 Feb 03 2025 17:04:46

%S 43,61,73,97,103,151,163,193,229,271,277,283,331,367,397,421,433,463,

%T 547,601,607,613,643,661,709,739,757,859,883,907,967,1021,1063,1093,

%U 1129,1171,1231,1237,1249,1279,1453,1489,1531,1543,1549,1579,1597,1609

%N Primes equal to 3*Sp - 2, where Sp is a semiprime.

%F a(n) = 3*A129926(n)-2. [_R. J. Mathar_, Apr 22 2010]

%t 3*Select[Range[600], PrimeOmega[#]==2&&PrimeQ[3#-2]&]-2 (* _James C. McMahon_, Feb 02 2025 *)

%K nonn,changed

%O 1,1

%A _Giovanni Teofilatto_, Jun 06 2007

%E Extended by _R. J. Mathar_, Apr 22 2010