OFFSET
1,1
COMMENTS
Or odd numbers k such that the arithmetic progression 6*k+1, 6*k+4, 6*k+7 consists of twice a semiprime sandwiched between two semiprimes.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
fQ[n_] := And[OddQ@ n, PrimeOmega@ n == 2]; Select[Range@ 1100,
AllTrue[{6 # + 1, 3 # + 2, 6 # + 7}, fQ] &] (* Michael De Vlieger, Nov 24 2015, Version 10 *)
PROG
(PARI) for(n=1, 1e4, if(n%2==1 && bigomega(6*n+1)==2 && bigomega(3*n+2)==2 && bigomega(6*n+7)==2, print1(n, ", "))); \\ Altug Alkan, Nov 24 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev and Peter J. C. Moses, Nov 24 2015
STATUS
approved