The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A079780 a(n) = largest prime <= n*prime(n). 2
 2, 5, 13, 23, 53, 73, 113, 151, 199, 283, 337, 443, 523, 601, 701, 839, 997, 1097, 1259, 1409, 1531, 1733, 1907, 2131, 2423, 2621, 2777, 2971, 3137, 3389, 3931, 4177, 4519, 4723, 5209, 5431, 5807, 6173, 6491, 6917, 7333, 7591, 8209, 8467, 8863, 9151, 9907 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) is the largest prime < A079779(n). LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 FORMULA a(n) = prime(A057855(n)). - Michel Marcus, Aug 30 2019 MAPLE With exception of first term: seq(prevprime(n*ithprime(n)), n=2..40); MATHEMATICA PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; Table[ Abs[ PrevPrim[ n*Prime[n]]], {n, 1, 50}] Table[Abs[NextPrime[n Prime[n], -1]], {n, 50}] (* Harvey P. Dale, May 25 2012 *) PROG (PARI) for(n=1, 47, print1(precprime(n*prime(n)), ", ")) CROSSREFS Cf. A057855, A079779. Sequence in context: A256491 A106009 A194552 * A178621 A309230 A048871 Adjacent sequences: A079777 A079778 A079779 * A079781 A079782 A079783 KEYWORD nonn AUTHOR Amarnath Murthy, Feb 03 2003 EXTENSIONS Edited and extended by Robert G. Wilson v, Klaus Brockhaus and Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 04 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 1 04:36 EST 2022. Contains 358454 sequences. (Running on oeis4.)