The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  X  0  X a*X a*X a^5*X a^5*X a^6*X a^6*X  0  X a*X a^2*X a^5*X a^2*X  0  X
 0  0  X a^6*X a^2*X a^4*X  X a^2*X a^6*X a^4*X a*X a^4*X a*X a*X a^3*X a^3*X a^3*X a^5*X

generates a code of length 18 over F8[X]/(X^2) who´s minimum homogenous weight is 112.

Homogenous weight enumerator: w(x)=1x^0+49x^112+217x^120+3584x^126+126x^128+35x^136+84x^144

The gray image is a linear code over GF(8) with n=144, k=4 and d=112.
This code was found by Heurico 1.16 in 0.0032 seconds.