The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  0  1  2  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1 2a^2  1  1  1  1  2  2  1  1  1
 0  1  1  a 3a^2+2 2a^2+3a+1 a^2+3a a^2+3a+3 3a^2+2a+3  a 3a^2+2 a^2+3a  1  0 2a^2+3a+1 3a^2+2a+3 2a^2+3 a^2+3a+3 3a^2+2 3a^2+2a+3 2a^2+3a+1  1 a^2+3a  1 a^2+3a+3 2a^2+3a+3 a^2+3a+1 a^2+3a+1 a^2+a 3a^2+2a+2  2 3a^2+2a 3a^2+3a+3 2a^2+3a+3 2a^2+3a+3 2a^2+3  0 3a^2+3 3a^2+3 a^2+a a^2+2a+1 2a^2+a+1 3a^2+2a+2 2a^2+3  a  2 2a+2 3a^2+2a+2 2a^2+2a+3 a+2 a+2  1 2a^2+2a+3 3a^2+2 3a^2+3 a^2+3  1  1  2  2  0
 0  0 2a^2+2  0  2  2 2a+2  2 2a^2 2a+2 2a^2+2 2a^2  2 2a^2+2a 2a^2+2a+2  0 2a^2+2a  2 2a 2a^2+2a+2 2a^2+2a+2 2a^2+2a  2 2a^2+2a+2  0 2a 2a 2a^2+2a+2 2a^2+2a 2a 2a^2 2a^2 2a+2 2a^2+2a+2  2 2a^2+2a+2  2 2a^2+2a+2 2a^2+2a  2 2a^2 2a^2  0 2a^2 2a+2 2a+2 2a^2+2 2a^2+2a+2  0 2a^2 2a^2+2 2a^2+2  0  0 2a^2+2a+2  0 2a^2+2a+2  0 2a 2a 2a
 0  0  0  2 2a^2+2 2a^2+2a+2 2a+2 2a^2 2a^2+2a+2 2a^2+2 2a^2+2 2a^2+2 2a^2+2a+2 2a+2 2a+2 2a^2 2a^2+2a+2 2a 2a^2 2a^2 2a^2+2a 2a  2  2 2a^2+2  2 2a^2+2 2a^2  2 2a+2 2a 2a+2  0 2a 2a 2a^2+2a+2 2a^2+2a+2  0 2a^2+2a+2 2a^2+2 2a+2 2a^2+2a+2 2a^2+2a 2a^2  0 2a+2  0 2a^2+2a+2  2 2a^2+2  2 2a^2+2a 2a^2+2 2a^2  2  2  0 2a+2  0 2a 2a^2+2a+2

generates a code of length 61 over GR(64,4) who´s minimum homogenous weight is 400.

Homogenous weight enumerator: w(x)=1x^0+322x^400+56x^401+56x^402+392x^403+448x^404+1932x^408+1904x^409+3416x^410+4424x^411+2520x^412+6230x^416+7392x^417+8232x^418+9464x^419+5880x^420+21875x^424+22288x^425+23240x^426+23576x^427+11144x^428+29820x^432+25704x^433+22400x^434+19488x^435+8680x^436+490x^440+259x^448+210x^456+126x^464+126x^472+42x^480+7x^488

The gray image is a code over GF(8) with n=488, k=6 and d=400.
This code was found by Heurico 1.16 in 14.4 seconds.