login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A341099 Numbers divisible by at least three members of A008864. 2
12, 18, 24, 30, 32, 36, 40, 42, 48, 54, 56, 60, 64, 72, 80, 84, 88, 90, 96, 102, 104, 108, 112, 114, 120, 126, 128, 132, 136, 138, 140, 144, 150, 152, 156, 160, 162, 168, 174, 176, 180, 186, 192, 196, 198, 200, 204, 208, 210, 216, 220, 222, 224, 228, 234, 240, 248, 252, 256, 258, 264, 270, 272 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers divisible by p+1 for at least three primes p.

Numbers k with A072627(k) >= 3.

Every positive multiple of a term is a term.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

a(4) = 30 is a term because it is divisible by 2+1=3, 5+1=6 and 29+1=30.

MAPLE

filter:= proc(n) local D;

  D:= convert(numtheory:-divisors(n), list);

  numboccur(true, map(t -> isprime(t-1), D))>= 3

end proc:

select(filter, [$1..1000]);

PROG

(PARI) isok(m) = sumdiv(m, d, isprime(d-1)) >= 3; \\ Michel Marcus, Feb 05 2021

CROSSREFS

Cf. A005101, A005835, A008864, A072627.

Sequence in context: A162151 A056773 A297925 * A175837 A136446 A074726

Adjacent sequences:  A341096 A341097 A341098 * A341100 A341101 A341102

KEYWORD

nonn

AUTHOR

J. M. Bergot and Robert Israel, Feb 04 2021

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 19 00:03 EDT 2021. Contains 343098 sequences. (Running on oeis4.)