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 A029708 Numbers k such that k-2 and k+2 are consecutive primes. 6
 9, 15, 21, 39, 45, 69, 81, 99, 105, 111, 129, 165, 195, 225, 231, 279, 309, 315, 351, 381, 399, 441, 459, 465, 489, 501, 615, 645, 675, 741, 759, 771, 825, 855, 861, 879, 885, 909, 939, 969, 1011, 1089, 1095, 1215, 1281, 1299, 1305, 1425, 1431 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are multiples of 3. Minimal first difference is 6. - Zak Seidov, May 15 2013 LINKS Marius A. Burtea, Table of n, a(n) for n = 1..10548 (first 1000 terms from Zak Seidov ) Zak Seidov, Table of n, a(n)/3 for n = 1..1000 FORMULA a(n) = (A029710(n) + A031505(n+1))/2 = A029710(n) + 2 = A031505(n+1) - 2. MATHEMATICA 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 *) Select[Range[9, 1432, 6], PrimeQ[#-2]&&PrimeQ[#+2]&] (* Zak Seidov, May 15 2013 - just for terms in DATA *) Mean/@Select[Partition[Prime[Range[300]], 2, 1], #[[2]]-#[[1]]==4&] (* Harvey P. Dale, Feb 15 2020 *) PROG (MAGMA) [k:k in [1..1500]| IsPrime(k-2) and NextPrime(k-2) eq k+2 ] // Marius A. Burtea, Jan 24 2019 CROSSREFS Essentially the same as A087679. Sequence in context: A336115 A072569 A072572 * A125215 A102739 A124622 Adjacent sequences:  A029705 A029706 A029707 * A029709 A029710 A029711 KEYWORD nonn AUTHOR STATUS approved

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Last modified May 14 18:54 EDT 2021. Contains 343900 sequences. (Running on oeis4.)