A079780 a(n) = largest prime <= n*prime(n).
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
Offset: 1
Keywords
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Maple
With exception of first term: seq(prevprime(n*ithprime(n)),n=2..40);
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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 *) -
PARI
for(n=1,47,print1(precprime(n*prime(n)),","))
Formula
a(n) = prime(A057855(n)). - Michel Marcus, Aug 30 2019
Extensions
Edited and extended by Robert G. Wilson v, Klaus Brockhaus and Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 04 2003
Comments