function s = an4( tt,T,omega1,n)
%UNTITLED2 Summary of this function goes here
%   Detailed explanation goes here

s=-6/T*(tt/n/omega1*sin(n*omega1*tt)+1/n/n/omega1/omega1*cos(n*omega1*tt))+...
    +34/T/n/omega1*sin(n*omega1*tt);

end
