OFFSET
1,1
COMMENTS
Conjecturally, the sequence is infinite.
LINKS
Peter J. C. Moses, Table of n, a(n) for n = 1..1000
EXAMPLE
65 = 5*13; 65 + 4 = 69 = 3*23. So 65 is in the sequence.
MATHEMATICA
Select[Range@ 500, And[SquareFreeQ@ #, PrimeOmega@ # == 2, SquareFreeQ[# + 4], PrimeOmega[# + 4] == 2] &] (* Michael De Vlieger, Jul 12 2015 *)
PROG
(PARI) main(size)={ v=vector(size); i=0; m=1; while(i<size, if(omega(m)==2&&omega(m+4)==2&&issquarefree(m)&&issquarefree(m+4), v[i++]=m); m++; ); return(v); } /* Anders Hellström, Jul 11 2015 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Jul 11 2015
EXTENSIONS
More terms from Peter J. C. Moses, Jul 11 2015
STATUS
approved