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A174385 Product of 3 consecutive odd numbers n such that n+-2 are primes. 1

%I #8 May 17 2018 10:54:10

%S 15,105,315,79335,148665,300495,1860375,1952625,3048045,6538455,

%T 14347935,57065085,82311135,83451705,169110165,223646115,335699595,

%U 347426115,410169435,674522625,736310715,1015071105,1655590755

%N Product of 3 consecutive odd numbers n such that n+-2 are primes.

%C All terms are divisible by 15. - _Robert Israel_, Apr 10 2018

%H Robert Israel, <a href="/A174385/b174385.txt">Table of n, a(n) for n = 1..10000</a>

%e 1*3*5=15 and 15+2 and 15-2 are primes, so 15=a(1) is in the sequence.

%e 3*5*7=105 and 105+2 and 105-2 are primes, so 105=a(2) is in the sequence.

%p select(t -> isprime(t+2) and isprime(t-2), [seq(n*(n+2)*(n+4),n=1..2000,2)]); # _Robert Israel_, Apr 10 2018

%t f[n_]:=n*(n+2)*(n+4);Select[Table[f[n],{n,1,7!,2}],PrimeQ[ #-2]&&PrimeQ[ #+2]&]

%t Select[Times@@@Partition[Range[1,1201,2],3,1],AllTrue[#+{2,-2},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, May 17 2018 *)

%Y Cf. A174383, A174384

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Mar 17 2010

%E Edited by _Robert Israel_, Apr 10 2018

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Last modified August 25 06:02 EDT 2024. Contains 375422 sequences. (Running on oeis4.)