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!)
A117096 Numbers n such that nextprime(2*n)<2*nextprime(n) (if p is prime then nextprime(p)=p). 0
1, 6, 8, 9, 14, 15, 18, 20, 21, 24, 25, 26, 30, 32, 33, 34, 35, 36, 38, 39, 44, 48, 49, 50, 51, 54, 55, 56, 62, 63, 64, 65, 68, 69, 74, 75, 76, 77, 78, 80, 81, 84, 85, 86, 90, 91, 92, 93, 94, 95, 96, 98, 99, 104, 105, 110, 111, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

if p is prime and nextprime(p*n)<nextprime(p)*nextprime(n) then n is composite

LINKS

Table of n, a(n) for n=1..67.

EXAMPLE

nextprime(2*6)=13 and nextprime(2)*nextprime(6)=2*7=14 then 6 is member because 13<14

PROG

(PARI) for(i=1, 150, if(nextprime(2*i)<nextprime(2)*nextprime(i), print1(i, ", ")))

CROSSREFS

Sequence in context: A304412 A161982 A285275 * A067812 A337543 A047394

Adjacent sequences:  A117093 A117094 A117095 * A117097 A117098 A117099

KEYWORD

easy,nonn

AUTHOR

Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 18 2006

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 February 25 12:00 EST 2021. Contains 341606 sequences. (Running on oeis4.)