The generator matrix

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

generates a code of length 47 over GR(64,4) who´s minimum homogenous weight is 288.

Homogenous weight enumerator: w(x)=1x^0+448x^288+1778x^296+2555x^304+3493x^312+3584x^315+4179x^320+50176x^323+5082x^328+175616x^331+5439x^336+4725x^344+3290x^352+1358x^360+392x^368+28x^376

The gray image is a code over GF(8) with n=376, k=6 and d=288.
This code was found by Heurico 1.16 in 28.6 seconds.