The generator matrix

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

generates a code of length 25 over GR(64,4) who´s minimum homogenous weight is 136.

Homogenous weight enumerator: w(x)=1x^0+217x^136+1029x^144+2163x^152+3528x^160+3584x^161+5292x^168+50176x^169+7329x^176+175616x^177+7735x^184+4193x^192+1281x^200

The gray image is a code over GF(8) with n=200, k=6 and d=136.
This code was found by Heurico 1.16 in 12.1 seconds.