The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  2  1  1  1
 0  2  0  0  0  2  2  2 2a  0  2 2a 2a 2a 2a  0  2 2a^2+2 2a^2+2a  0
 0  0  2  0  0 2a^2+2 2a^2+2a+2 2a^2+2a 2a^2+2a  2 2a+2 2a^2+2  0  2 2a^2+2a+2 2a 2a+2  0 2a^2+2  0
 0  0  0  2  0  2 2a^2+2a+2 2a 2a+2 2a^2 2a^2+2  0 2a^2+2a+2  2 2a 2a^2+2a 2a+2 2a^2  2  0
 0  0  0  0  2 2a^2+2 2a+2 2a 2a^2+2a+2 2a 2a^2 2a^2 2a+2  0 2a  2 2a^2 2a^2+2a 2a+2  0

generates a code of length 20 over GR(64,4) who´s minimum homogenous weight is 104.

Homogenous weight enumerator: w(x)=1x^0+273x^104+1211x^112+2387x^120+3836x^128+28672x^133+6895x^136+200704x^141+9205x^144+6349x^152+2611x^160

The gray image is a code over GF(8) with n=160, k=6 and d=104.
This code was found by Heurico 1.16 in 8.44 seconds.