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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A080188 Primes p such that 13 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248). 1
23, 311, 349, 857, 1091, 1871, 1949, 2027, 2339, 2729, 3119, 3821, 5849, 6551, 7487, 9437, 10139, 10529, 11699, 15287, 18251, 21059, 21839, 38609, 42899, 49919, 51479, 57329, 61151, 65519, 69497, 70199, 70979, 81899, 97499, 108107, 109199, 114659 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence appears to consist of 23, 349 and the lesser of twin primes q (A001359) such that q+1 is 13-smooth (A080197) but not 11-smooth (A051038, A080196).

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

349 is a term since 350 = 2*5^2*7, 351 = 3^3*13, 352 = 2^5*11 are the numbers between 349 and the next prime 353; 857 is a term since 858 = 2*3*11*13 is the only number between 857 and the next prime 859.

PROG

(PARI) {forprime(p=2, 120000, q=nextprime(p+1); m=0; j=p+1; while(j<q&&m<=13, f=factor(j); a=f[matsize(f)[1], 1]; if(m<a, m=a); j++); if(m==13, print1(p, ", ")))}

CROSSREFS

Cf. A052248, A001359, A080197, A051038, A080196.

Sequence in context: A086558 A090927 A045530 * A142433 A234234 A125458

Adjacent sequences:  A080185 A080186 A080187 * A080189 A080190 A080191

KEYWORD

nonn

AUTHOR

Klaus Brockhaus, Feb 10 2003

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 August 18 22:08 EDT 2019. Contains 326109 sequences. (Running on oeis4.)