OFFSET
1,4
COMMENTS
when n increases sum k(n) for i=1 to n / sum n for i=1 to n tends to log(7)/3.7
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..1000
EXAMPLE
1*7^1*(7^1-1)-1=41 prime as 43 so k(1)=1
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Dec 18 2008
STATUS
approved