The generator matrix

 1  0  1  1  1  1  1  1  1  0  1  1  0  1  1  1  1  1
 0  1  1  a a+1  0 (a+1)X+1  a (a+1)X+a+1  1 (a+1)X+1  a  1 (a+1)X+a+1 (a+1)X+a+1  0 (a+1)X+1  0
 0  0 (a+1)X  0  0  0  0  X  X  X aX  0  X (a+1)X (a+1)X  X (a+1)X  0
 0  0  0  X  0  0  X (a+1)X  X (a+1)X  0  X  X  0 aX  0 aX  0
 0  0  0  0 (a+1)X  0 aX  0 aX aX  X (a+1)X aX (a+1)X  X (a+1)X (a+1)X  0
 0  0  0  0  0  X aX aX (a+1)X (a+1)X aX  0  X  0  0 aX aX  0

generates a code of length 18 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 36.

Homogenous weight enumerator: w(x)=1x^0+75x^36+240x^40+288x^42+381x^44+384x^45+2304x^46+528x^48+3456x^49+7488x^50+669x^52+10368x^53+13824x^54+858x^56+10368x^57+12960x^58+723x^60+435x^64+168x^68+18x^72

The gray image is a linear code over GF(4) with n=72, k=8 and d=36.
This code was found by Heurico 1.16 in 3.4 seconds.