OFFSET
1,3
COMMENTS
The number of roots of the equation is determined graphically. It is equal to the number of intersection points of two graphs: y = n*cos(x) and y = sqrt(x).
LINKS
Nicolay Avilov, Illustration for a(4).
FORMULA
Conjecture: a(n) = 2*floor(n^2/(2*Pi)) + 1.
EXAMPLE
a(4) = 5 because the equation 4*cos(x) = sqrt(x) has 5 roots. See link.
CROSSREFS
KEYWORD
nonn
AUTHOR
Nicolay Avilov, Mar 27 2023
STATUS
approved