The generator matrix

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

generates a code of length 18 over GR(16,4) who´s minimum homogenous weight is 36.

Homogenous weight enumerator: w(x)=1x^0+72x^36+255x^40+372x^44+495x^48+702x^52+12288x^54+879x^56+696x^60+432x^64+174x^68+18x^72

The gray image is a code over GF(4) with n=72, k=7 and d=36.
This code was found by Heurico 1.16 in 0.421 seconds.