The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
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!)
A141109 Even numbers 2n such that for every prime p in [n,2n-2], 2n-p is also prime. 1
4, 6, 8, 10, 12, 14, 16, 18, 24, 30, 36, 42, 48, 60, 90, 210 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The Deshouillers et al. paper proves that 210 is the last term. This sequence is the same as 2*A002271, but why?
LINKS
Jean-Marc Deshouillers, Andrew Granville, Wladyslaw Narkiewicz and Carl Pomerance, An upper bound in Goldbach's problem, Math. Comp. 61 (1993), 209-213.
EXAMPLE
30 is in this sequence because the primes p between 15 and 28 are {17,19,23} and 30-p is {13,11,7}.
MATHEMATICA
t={}; Do[If[And@@PrimeQ[2n-Prime[Range[PrimePi[n-1]+1, PrimePi[2n-2]]]], AppendTo[t, 2n]], {n, 2, 105}]; t
CROSSREFS
Sequence in context: A353537 A134928 A279040 * A333197 A289426 A186331
KEYWORD
fini,full,nonn
AUTHOR
T. D. Noe, Jun 03 2008
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 May 24 23:50 EDT 2024. Contains 372782 sequences. (Running on oeis4.)