login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075589 Primes p such that the number of distinct prime divisors of all composite numbers between p and the next prime is 9. 10

%I #21 Sep 08 2022 08:45:07

%S 89,151,233,257,263,271,353,367,373,503,541,571,587,601,647,653,727,

%T 733,751,977,991,1013,1181,1291,1321,1433,1453,1621,1753,1861,2281,

%U 2371,2377,2671,3061,3079,3203,3323,3793,4051,4073,4283,4357,4519,4591,4639

%N Primes p such that the number of distinct prime divisors of all composite numbers between p and the next prime is 9.

%H Amiram Eldar, <a href="/A075589/b075589.txt">Table of n, a(n) for n = 1..10000</a>

%e For p = 233, the next prime number is 239. The numbers between 233 and 237 and the prime divisors are respectively 234 {2, 3, 13}, 235 {5, 47}, 236 {2, 59}, 237 {3, 79 }, 238 {2, 7, 17}. The set of prime divisors is {2, 3, 5, 7, 13, 17, 47, 59, 79} and has 9 elements, so 233 is a term.

%o (Magma) a:=[]; for p in PrimesInInterval(2,5000) do b:={}; for s in [p..NextPrime(p)-1] do if not IsPrime(s) then b:=b join Set(PrimeDivisors(s)); end if; end for; if #Set(b) eq 9 then Append(~a,p); end if; end for; a; // _Marius A. Burtea_, Sep 26 2019

%Y Cf. A052297, A075581, A075580, A059960, A075583, A075584, A075585, A075586, A075587, A075588.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Sep 26 2002

%E More terms from _Matthew Conroy_, Apr 30 2003

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 25 01:35 EDT 2024. Contains 371964 sequences. (Running on oeis4.)