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A161945 Numbers n with property that three consecutive odd numbers {n,n+2,n+4} are all composite. 6
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 13 23:48 EST 2019. Contains 329106 sequences. (Running on oeis4.)