OFFSET
0,26
COMMENTS
Let f(n) = number of (nontrivial) zeros of zeta(z) with 0 < Im(z) < n; then f(n) ~ a(n).
The sequence gives exactly the values of A072080(n) for n = 2, 3, and 5.
FORMULA
a(n) = floor((LogGamma(n/2+1) - n*log(Pi)/2)/Pi).
MATHEMATICA
Table[Floor[(LogGamma[n/2 + 1] - n*Log[Pi]/2)/Pi], {n, 0, 74}]
PROG
(PARI) a(n)=floor((lngamma(n/2+1)-n*log(Pi)/2)/Pi)
CROSSREFS
KEYWORD
sign
AUTHOR
Arkadiusz Wesolowski, Nov 08 2015
STATUS
approved