A321495 Numbers k such that k and k+1 have at least 5 but not both exactly 5 distinct prime factors.

728364, 1565564, 1774409, 1817529, 1923635, 2162094, 2187185, 2199834, 2225894, 2369850, 2557190, 2594514, 2659734, 2671305, 2794154, 2944689, 2964884, 3126045, 3139730, 3170244, 3244955, 3273809, 3279639, 3382379, 3387054, 3506810, 3555110, 3585945, 3686969, 3711630

Offset

1,1

Comments

Complement of A140079 (k and k+1 have exactly 5 distinct prime factors) in A321505 (k and k+1 have at least 5 distinct prime factors).

Links

Table of n, a(n) for n=1..30.

Formula

A321505 \ A140079.

Mathematica

aQ[n_]:=Module[{v={PrimeNu[n], PrimeNu[n+1]}}, Min[v]>4 && v!={5, 5}]; Select[Range[120000], aQ] (* Amiram Eldar, Nov 12 2018 *)

Prog

(PARI) is(n)=vecmin(n=[omega(n), omega(n+1)])>4&&n!=[5, 5]

Crossrefs

Cf. A140079, A321505; A321494, A321496 (analog for 4 & 6 factors).

Sequence in context: A250153 A252324 A204150 * A234495 A156867 A156868

Adjacent sequences: A321492 A321493 A321494 * A321496 A321497 A321498

Keyword

nonn

Author

M. F. Hasler, Nov 12 2018

Status

approved