OFFSET
1,2
COMMENTS
The fact that a(n)/n diverges (it is greater than sqrt(n)) implies sum_{k>=1} 1/sqrt(k) is not Cesaro summable.
LINKS
Balarka Sen, Table of n, a(n) for n = 1..500
FORMULA
a(n) ~ 2*sum_{k=1..n} sqrt(k) ~ (4/3) n^(3/2).
PROG
(PARI) for(n=1, 100, print1(floor(sum(i=1, n, sum(j=1, i, 1/sqrt(j))))", "))
(PARI) a(n)=sum(j=1, n, (n+1-j)/sqrt(j))\1 \\ Charles R Greathouse IV, May 02 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Balarka Sen, Apr 30 2013
STATUS
approved