Magnetization for square lattice.

Terms

a(0) =1a(1) =0a(2) =-2a(3) =-8a(4) =-34a(5) =-152a(6) =-714a(7) =-3472a(8) =-17318a(9) =-88048a(10) =-454378a(11) =-2373048a(12) =-12515634a(13) =-66551016a(14) =-356345666a(15) =-1919453984a(16) =-10392792766a(17) =-56527200992a(18) =-308691183938