The generator matrix

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

generates a code of length 20 over F8[X]/(X^2) who´s minimum homogenous weight is 120.

Homogenous weight enumerator: w(x)=1x^0+392x^120+847x^128+3584x^133+672x^136+25088x^141+952x^144+952x^152+280x^160

The gray image is a linear code over GF(8) with n=160, k=5 and d=120.
This code was found by Heurico 1.16 in 0.146 seconds.