|
%I #28 Sep 08 2022 08:44:50
%S 9,15,21,39,45,69,81,99,105,111,129,165,195,225,231,279,309,315,351,
%T 381,399,441,459,465,489,501,615,645,675,741,759,771,825,855,861,879,
%U 885,909,939,969,1011,1089,1095,1215,1281,1299,1305,1425,1431
%N Numbers k such that k-2 and k+2 are consecutive primes.
%C All terms are multiples of 3. Minimal first difference is 6. - _Zak Seidov_, May 15 2013
%H Marius A. Burtea, <a href="/A029708/b029708.txt">Table of n, a(n) for n = 1..10548</a> (first 1000 terms from Zak Seidov )
%H Zak Seidov, <a href="/A029708/a029708.txt">Table of n, a(n)/3 for n = 1..1000</a>
%F a(n) = (A029710(n) + A031505(n+1))/2 = A029710(n) + 2 = A031505(n+1) - 2.
%t f[n_]:=PrimeQ[n-2]&&PrimeQ[n+2]; lst={};Do[If[f[n],AppendTo[lst,n]],{n,7,8!,2}];lst (* _Vladimir Joseph Stephan Orlovsky_, Oct 09 2009 *)
%t Select[Range[9,1432,6],PrimeQ[#-2]&&PrimeQ[#+2]&] (* _Zak Seidov_, May 15 2013 - just for terms in DATA *)
%t Mean/@Select[Partition[Prime[Range[300]],2,1],#[[2]]-#[[1]]==4&] (* _Harvey P. Dale_, Feb 15 2020 *)
%o (Magma) [k:k in [1..1500]| IsPrime(k-2) and NextPrime(k-2) eq k+2 ] // _Marius A. Burtea_, Jan 24 2019
%Y Essentially the same as A087679.
%K nonn
%O 1,1
%A _N. J. A. Sloane_
|
