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A079364 Composite numbers having two composite neighbors. 7

%I #25 Jan 15 2015 15:01:18

%S 9,15,21,25,26,27,33,34,35,39,45,49,50,51,55,56,57,63,64,65,69,75,76,

%T 77,81,85,86,87,91,92,93,94,95,99,105,111,115,116,117,118,119,120,121,

%U 122,123,124,125,129,133,134,135,141,142,143,144,145,146,147,153,154,155

%N Composite numbers having two composite neighbors.

%C In other words, composite numbers that are not nearest-neighbors of primes. - _Omar E. Pol_, Jan 02 2009

%C Complement of A210940. - _Omar E. Pol_, Apr 18 2012

%H Reinhard Zumkeller, <a href="/A079364/b079364.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[6! ],!PrimeQ[ # ]&&!PrimeQ[ #-1]&&!PrimeQ[ #+1]&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 26 2010 *)

%t With[{r=Complement[Range[160],Prime[Range[PrimePi[160]]]]}, Transpose[ Select[ Partition[r,3,1], Differences[#]=={1,1}&]][[2]]] (* _Harvey P. Dale_, Feb 05 2012 *)

%o (Haskell)

%o a079364 n = a079364_list !! (n-1)

%o a079364_list = filter

%o (\x -> a010051' (x - 1) == 0 && a010051' (x + 1) == 0) a002808_list

%o -- _Reinhard Zumkeller_, Jan 10 2013

%Y Cf. A000040, A002808, A014574, A045718.

%Y Cf. A010051, A221309 (subsequence).

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Feb 15 2003

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)