A161945 Numbers n with property that three consecutive odd numbers {n,n+2,n+4} are all composite.

91, 115, 117, 119, 121, 141, 143, 183, 185, 201, 203, 205, 213, 215, 217, 243, 245, 285, 287, 295, 297, 299, 301, 319, 321, 323, 325, 339, 341, 361, 391, 403, 411, 413, 423, 425, 451, 469, 471, 473, 481, 493, 511, 513, 515, 525, 527, 529, 531, 533, 535, 549

Offset

1,1

Links

Table of n, a(n) for n=1..52.

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

Sequence in context: A294742 A224981 A261260 * A140389 A236845 A157345

Adjacent sequences: A161942 A161943 A161944 * A161946 A161947 A161948

Keyword

nonn

Author

Zak Seidov, Jun 22 2009

Status

approved