login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A080185 Primes p such that 5 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248). 1

%I

%S 7,29,59,149,179,239,269,599,809,1619,2999,4049,4799,8999,9719,15359,

%T 21599,23039,33749,138239,179999,281249,345599,737279,3455999,6143999,

%U 6560999,10124999,13668749,15551999,17495999,20995199,22118399,23999999

%N Primes p such that 5 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248).

%C The sequence consists of 7 and the lesser of twin primes q (A001359) such that q+1 is 5-smooth (A051037) but not 3-smooth (A003586, A080193).

%e 7 is a term since 8 = 2^3, 9 = 3^3, 10 = 2*5 are the numbers between 7 and the next prime 11; 149 is a term since 150 = 2*3*5^2 is the only number between 149 and the next prime 151.

%o (PARI) {forprime(p=2,24000000,q=nextprime(p+1); m=0; j=p+1; while(j<q&&m<=5,f=factor(j); a=f[matsize(f)[1],1]; if(m<a,m=a); j++); if(m==5,print1(p,",")))}

%Y Cf. A052248, A001359, A051037, A003586, A080193.

%K nonn

%O 1,1

%A _Klaus Brockhaus_, Feb 10 2003

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 August 26 05:50 EDT 2019. Contains 326330 sequences. (Running on oeis4.)