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A321495 Numbers k such that k and k+1 have at least 5 but not both exactly 5 distinct prime factors. 6
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 4 13:35 EDT 2020. Contains 335448 sequences. (Running on oeis4.)