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%I #12 Apr 10 2021 05:50:47
%S 1870,2090,2470,2530,2990,3190,3410,3458,3740,3770,3910,4030,4070,
%T 4180,4186,4510,4730,4810,4930,4940,5060,5170,5187,5270,5278,5330,
%U 5474,5510,5590,5642,5830,5890,5980,6110,6279,6290,6380,6490,6710,6734,6820,6890
%N Numbers having exactly three prime gaps in their factorization.
%H Reinhard Zumkeller, <a href="/A073495/b073495.txt">Table of n, a(n) for n = 1..10000</a>
%F A073490(a(n)) = 3.
%e 1870 is a term, as 1870 = 2*5*11*17 with three gaps: between 2 and 5, between 5 and 11 and between 11 and 17.
%t q[n_] := SequenceCount[FactorInteger[n][[;; , 1]], {p1_, p2_} /; p2 != NextPrime[p1], Overlaps -> True] == 3; Select[Range[7000], q] (* _Amiram Eldar_, Apr 10 2021*)
%o (Haskell)
%o a073495 n = a073495_list !! (n-1)
%o a073495_list = filter ((== 3) . a073490) [1..]
%o -- _Reinhard Zumkeller_, Dec 20 2013
%Y Cf. A005117, A073490, A073492, A073493, A073494, A073489.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Aug 03 2002
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