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%I #9 Dec 21 2013 05:52:34
%S 110,130,170,182,190,220,230,238,260,266,273,290,310,322,340,357,364,
%T 370,374,380,399,406,410,418,430,434,440,460,470,476,483,494,506,518,
%U 520,530,532,546,550,561,574,580,590,598,602,609,610,620,627,638,644
%N Numbers having exactly two prime gaps in their factorization.
%C A073490(a(n)) = 2.
%H Reinhard Zumkeller, <a href="/A073494/b073494.txt">Table of n, a(n) for n = 1..10000</a>
%e 220 is a term, as 220 = 2*2*5*11 with two gaps: between 2 and 5 and between 5 and 11.
%t pa[n_, k_] := If[k == NextPrime[n], 0, 1]; Select[Range[645], Total[pa @@@ Partition[First /@ FactorInteger[#], 2, 1]] == 2 &] (* _Jayanta Basu_, Jul 01 2013 *)
%o (Haskell)
%o a073494 n = a073494_list !! (n-1)
%o a073494_list = filter ((== 2) . a073490) [1..]
%o -- _Reinhard Zumkeller_, Dec 20 2013
%Y Cf. A005117, A073492, A073493, A073495, A073488.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Aug 03 2002
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