OFFSET
1,2
COMMENTS
Limit_{n->oo} a(n)/n^2 = Pi/4 = 0.78539816...
FORMULA
a(n) = floor(Sum_{k=0..n-1} sqrt(A094728(n,k))).
EXAMPLE
A094728(4) is (16, 15, 12, 7). Hence, a(4) = floor(sqrt(16) + sqrt(15) + sqrt(12) + sqrt(7)) = floor(13.9828...) = 13.
MATHEMATICA
Table[Floor[Sum[Sqrt[n^2 - k^2], {k, 0, n - 1}]], {n, 60}] (* T. D. Noe, Mar 19 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Mar 07 2013
EXTENSIONS
a(16)-a(50) from Giovanni Resta, Mar 19 2013
STATUS
approved