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%I #21 Oct 11 2023 17:21:25
%S 6,8,12,16,20,22,24,26,36,38,42,46,48,50,52,54,56,60,68,70,74,78,84,
%T 90,94,96,98,102,106,110,112,114,120,128,144,146,150,152,160,162,164,
%U 172,174,184,186,188,190,194,198,204,210,214,216,232,234,236,246,252,262
%N Even numbers k such that k-2 and k+2 have the same number of distinct prime factors.
%H Amiram Eldar, <a href="/A115166/b115166.txt">Table of n, a(n) for n = 1..10000</a>
%e 38 is in the sequence because 36 = 2^2 * 3^2 and 40 = 2^3 * 5.
%p with(numtheory): a:=proc(n) if nops(factorset(n-2))=nops(factorset(n+2)) then n else fi end: seq(a(2*n),n=2..133); # _Emeric Deutsch_, Mar 12 2006
%t Select[Range[2, 262, 2], PrimeNu[# - 2] == PrimeNu[# + 2] &] (* _Amiram Eldar_, Feb 18 2020 *)
%t Select[Mean/@SequencePosition[PrimeNu[Range[300]],{x_,_,_,_,x_}],EvenQ] (* _Harvey P. Dale_, Oct 11 2023 *)
%o (PARI) g(n) = forstep(x=4,n,2,p1=omega(x-2); p2=omega(x+2); if(p1==p2,print(x",")))
%o (Magma) [k:k in [4.. 270 by 2]| #PrimeDivisors(k-2) eq #PrimeDivisors(k+2)]; // _Marius A. Burtea_, Feb 18 2020
%Y Cf. A001221.
%Y Subsequence of A005843.
%K easy,nonn
%O 1,1
%A _Cino Hilliard_, Mar 03 2006
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