The generator matrix

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

generates a code of length 15 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 36.

Homogenous weight enumerator: w(x)=1x^0+60x^36+36x^37+48x^39+402x^40+180x^41+288x^43+1011x^44+300x^45+432x^47+1029x^48+252x^49+30x^52+24x^56+3x^60

The gray image is a linear code over GF(4) with n=60, k=6 and d=36.
This code was found by Heurico 1.16 in 0.0154 seconds.