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!)
A115988 Powers of 3 which are the average of two primes p and nextprime(p). 4
9, 81, 387420489, 3486784401, 7509466514979724803946715958257547, 147808829414345923316083210206383297601 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ray Chandler, Table of n, a(n) for n = 1..13

EXAMPLE

Nextprime(387420479) = 387420499 and (387420479 + 387420499)/2 = 387420489 = 3^18, so 387420489 belongs to the sequence.

PROG

(PARI) lista(nn) = for(k=1, nn, if(precprime(3^k-1)+nextprime(3^k+1)==2*3^k, print1(3^k, ", "))); \\ Jinyuan Wang, Feb 26 2020

CROSSREFS

Cf. A115986, A115987, A115989.

Sequence in context: A067216 A076088 A061211 * A067506 A263816 A345143

Adjacent sequences:  A115985 A115986 A115987 * A115989 A115990 A115991

KEYWORD

nonn

AUTHOR

Giovanni Resta, Feb 10 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 9 09:22 EDT 2022. Contains 356021 sequences. (Running on oeis4.)