OFFSET
1,1
EXAMPLE
143 is in the sequence because 143=11*13, 145=5*29, 147=3*49. [Emeric Deutsch, Jun 27 2009]
MAPLE
a:= proc(n) if not (isprime(2*n-1) or isprime(2*n+1) or isprime(2*n+3)) then 2*n-1 end if end proc: seq(a(n), n = 2 .. 300); # Emeric Deutsch, Jun 27 2009
MATHEMATICA
fQ[n_]:=!PrimeQ[n]&&!PrimeQ[n+2]&&!PrimeQ[n+4]; Select[Range[3, 1000, 2], fQ] (* Vladimir Joseph Stephan Orlovsky, Apr 16 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Jun 22 2009
STATUS
approved