N = 3X+1 = 3*((3Y+1)/2)+1 = 3*((3*((3z+1)/2)+1)/2) +1 = (27z+19)/4
when z =3, N =25; z=7, N=25+27...
z = 3+4x...
N=25+27x...
N = 3X+1 = 3*((3Y+1)/2)+1 = 3*((3*((3z+1)/2)+1)/2) +1 = (27z+19)/4
when z =3, N =25; z=7, N=25+27...
z = 3+4x...
N=25+27x...