OFFSET
1,1
COMMENTS
All but the first term are even.
MATHEMATICA
Select[Range[750], PrimeOmega[# + 3] == PrimeOmega[# - 3] == 2 &] (* Vincenzo Librandi, Mar 28 2015 *)
SequencePosition[Table[If[PrimeOmega[n]==2, 1, 0], {n, 800}], {1, _, _, _, _, _, 1}][[All, 1]]+3 (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 21 2017 *)
PROG
(PARI) lista(nn, m=3) = {for (n=m+1, nn, if (bigomega(n-m)==2 && bigomega(n+m)==2, print1(n, ", ")); ); }
(Magma) IsSemiprime:=func< n | &+[k[2]: k in Factorization(n)] eq 2 >; [ n: n in [4..750] | IsSemiprime(n+3) and IsSemiprime(n-3) ]; // Vincenzo Librandi, Mar 28 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Mar 27 2015
STATUS
approved