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!)
A090188 Primes P such that P=k*p(n)#-p(n+1) is prime for least k. Here p(i)# denotes the i-th primorial and p(i) denotes the i-th prime. 1
3, 7, 23, 199, 2297, 30013, 1021001, 9699667, 669278581, 32348466119, 401120980223, 29682952539199, 1825501581163217, 39248283995010043, 3074448912942456997, 228124109340330313051, 49991769104009528615759 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
k*p(n)#-p(n+1) is the greatest prime < k*p(n)#-p(n+1)-1 and if k*p(n)#-p(n+1)-1 is not prime it is the greatest prime < k*p(n)#-p(n+1). Values for k are given in A090189.
LINKS
EXAMPLE
1*2*3*5*7*11*13-17=30013, 1*p(6)#-p(7)=30013, 1 is the least k for n=6
30013 is prime P for n=6.
PROG
(PARI) a(n)=my(P=prod(i=1, n, prime(i)), q=prime(n+1), k); while(!ispseudoprime(P*k++ - q), ); k*P-q \\ Charles R Greathouse IV, Feb 07 2013
CROSSREFS
Sequence in context: A262264 A060235 A343815 * A001773 A067604 A090118
KEYWORD
base,nonn
AUTHOR
Pierre CAMI, Jan 21 2004
EXTENSIONS
a(14) corrected by Charles R Greathouse IV, Feb 07 2013
STATUS
approved

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 March 29 07:27 EDT 2024. Contains 371265 sequences. (Running on oeis4.)