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Numbers having no divisors d such that also d+2 is a divisor.
5

%I #16 May 23 2020 05:25:53

%S 1,2,5,7,10,11,13,14,17,19,22,23,25,26,29,31,34,37,38,41,43,46,47,49,

%T 50,53,55,58,59,61,62,65,67,71,73,74,77,79,82,83,85,86,89,91,94,95,97,

%U 98,101,103,106,107,109,110,113,115,118,119,121,122,125,127,130,131,133

%N Numbers having no divisors d such that also d+2 is a divisor.

%C Except for 3, all primes are in this sequence. - _Alonso del Arte_, Jun 13 2014

%H Amiram Eldar, <a href="/A099477/b099477.txt">Table of n, a(n) for n = 1..10000</a>

%F A099475(a(n)) = 0.

%e 10 is in the sequence because its divisors are 1, 2, 5, 10, none of which is 2 less than another.

%e 11 is in the sequence as are all primes other than 3.

%e 12 is not in the sequence because its divisors are 1, 2, 3, 4, 6, 12, of which 2 and 4 are 2 less than another divisor.

%t twinDivsQ[n_] := Union[ IntegerQ[ # ] & /@ (n/(Divisors[n] + 2))][[ -1]] == True; Select[ Range[133], !twinDivsQ[ # ] &] (* _Robert G. Wilson v_, Jun 09 2005 *)

%t d2noQ[n_]:=Module[{d=Divisors[n]},Intersection[d,d+2]=={}]; Select[ Range[ 150],d2noQ] (* _Harvey P. Dale_, Feb 15 2019 *)

%Y Complement of A059267.

%Y Cf. A099475, A108118.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Oct 18 2004