A141711 Carmichael numbers with more than 3 prime factors.

41041, 62745, 63973, 75361, 101101, 126217, 172081, 188461, 278545, 340561, 449065, 552721, 656601, 658801, 670033, 748657, 825265, 838201, 852841, 997633, 1033669, 1050985, 1082809, 1569457, 1773289, 2100901, 2113921, 2433601

Offset

1,1

Comments

Sequence A087788 gives Carmichael numbers with exactly 3 prime factors; since they cannot have fewer (cf. references in A002997), this sequence is the complement of A087788 in A002997.

The terms preceding a(17) = 825265 = A006931(5) have exactly 4 prime factors. See A112428 - A112432 for Carmichael numbers with exactly 5, ..., 9 prime factors. - M. F. Hasler, Apr 14 2015

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

A141711 = A002997 \ A087788 = A074379 U A112428 U A112429 U A112430 U A112431 U A112432 U ...

Example

a(17)=825265 is the least Carmichael number having more than 4 divisors, thus the sequence differs from A074379 only from that term on.

Mathematica

ok[n_] :=  Divisible[n - 1, CarmichaelLambda[n]] && Length[FactorInteger[n]] > 3; Select[ Range[3*10^6], ok] (* Jean-François Alcover, Sep 23 2011 *)

Prog

(PARI) A2997=readvec("b002997.gp"); A002997(n)=A2997[n]; for( n=1, 100, omega( A002997(n) ) > 3 & print1( A002997(n)", "))

Crossrefs

Cf. A002997, A087788, A074379, A112428 - A112432, A006931.

Sequence in context: A033532 A173361 A047828 * A074379 A237395 A252121

Adjacent sequences: A141708 A141709 A141710 * A141712 A141713 A141714

Keyword

nonn

Author

M. F. Hasler, Jul 01 2008

Status

approved