OFFSET
1,2
COMMENTS
Equivalently, for n > 1, a(n) is the smallest number not already in the sequence such that the arithmetic mean of the first n terms is prime. - Derek Orr, Jun 26 2015
Conjectured not to be a permutation of the natural numbers. The numbers that have not been used before the 2000th term: 4, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, ... - Derek Orr, Jun 26 2015
LINKS
Derek Orr, Table of n, a(n) for n = 1..2000
PROG
(PARI) v=[1]; n=1; while(#v<200, s=(n+vecsum(v))/(#v+1); if(type(s)=="t_INT", if(isprime(s)&&!vecsearch(vecsort(v), n), v=concat(v, n); n=0)); n++); v \\ Derek Orr, Jun 26 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Aug 16 2002
EXTENSIONS
Corrected and extended by Sascha Kurz, Feb 01 2003
STATUS
approved