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!)
A087821 Sequence of primes P(i) such that P=(j*P(i)#)/2 - 2 and P+4 are consecutive primes, where j is odd, 0 < j < P(i+1) and P(i) denotes i-th prime. 2
3, 5, 5, 7, 7, 11, 13, 13, 13, 17, 17, 23, 29, 31, 31, 43, 43, 47, 53, 53, 61, 73, 83, 89, 89, 103, 131, 131, 173, 223, 227, 241, 251, 257, 311, 331, 359, 443, 523 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

I think I have a proof that the sequence is infinite.

LINKS

Table of n, a(n) for n=0..38.

EXAMPLE

(3*2*3*5*7*11*13*17)/2 - 2 = 765763 and (3*2*3*5*7*11*13*17)/2 + 2 = 765767 are gap 4 primes, with j=3, i=7, P(i)=17.

CROSSREFS

Cf. A087820, A087822.

Sequence in context: A242189 A302756 A305216 * A204894 A109258 A088081

Adjacent sequences:  A087818 A087819 A087820 * A087822 A087823 A087824

KEYWORD

nonn,more

AUTHOR

Pierre CAMI, Oct 06 2003

EXTENSIONS

Edited by Ray Chandler, Oct 19 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 September 26 05:00 EDT 2020. Contains 337346 sequences. (Running on oeis4.)