Nuttall-defined minimum 4-term Blackman-Harris window
w = nuttallwin(N)
w = nuttalwin(N,SFLAG)
w = nuttallwin(N) returns a Nuttall defined N-point, 4-term symmetric Blackman-Harris window in the column vector w. The window is minimum in the sense that its maximum sidelobes are minimized. The coefficients for this window differ from the Blackman-Harris window coefficients computed with blackmanharris and produce slightly lower sidelobes.
w = nuttalwin(N,SFLAG) uses SFLAG window sampling. SFLAG can be 'symmetric' or 'periodic'. The default is 'symmetric'. You can find the equations defining the symmetric and periodic windows in Definitions.
Compare 64-point Blackman-Harris and Nuttall's Blackman-Harris windows and plot them using WVTool:
L = 64; w = blackmanharris(L); y = nuttallwin(L); wvtool(w,y)
The maximum difference between the two windows is
max(abs(y-w)) ans = 0.0099
The equation for the symmetric Nuttall defined 4-term Blackman-Harris window is
where n= 0,1,2, ... N-1.
The equation for the periodic Nuttall defined 4-term Blackman-Harris window is
where n= 0,1,2, ... N-1. The periodic window is N-periodic.
The coefficients for this window are
a0 = 0.3635819
a1 = 0.4891775
a2 = 0.1365995
a3 = .0106411
 Nuttall, Albert H. "Some Windows with Very Good Sidelobe Behavior." IEEE® Transactions on Acoustics, Speech, and Signal Processing. Vol. ASSP-29 (February 1981). pp. 84-91.