%I #16 Nov 13 2018 12:47:21

%S 38570,40754,51414,51765,58695,60605,62985,66044,68585,70889,71070,

%T 73185,73814,74865,77349,82004,83265,83720,83979,85085,87009,90804,

%U 90915,91805,91884,92378,94094,94829,96459,97565,98769,98889,100814,101269,101660,104005,104754,105468,107184,108030,108185,108965

%N Numbers k such that k and k+1 have at least 4 but not both exactly 4 distinct prime factors.

%C A321504 lists numbers n such that k and k+1 both have at least 4 distinct prime factors, while A140078 lists numbers such that k and k+1 have exactly 4 distinct prime factors. This sequence is the complement of the latter in the former, it consists of terms with indices (124, 214, 219, 276, 321, 415, ...) of the former.

%F A321504 \ A140078.

%t aQ[n_]:=Module[{v={PrimeNu[n],PrimeNu[n+1]}},Min[v]>3 && v!={4,4}]; Select[Range[120000], aQ] (* _Amiram Eldar_, Nov 12 2018 *)

%o (PARI) is(n)=vecmin(n=[omega(n),omega(n+1)])>=4&&n!=[4,4]

%Y Cf. A140078, A321504; A321493, A321496 (analog for 3 & 5 factors).

%K nonn

%O 1,1

%A _M. F. Hasler_, Nov 12 2018