The generator matrix

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

generates a code of length 21 over F8[X]/(X^2) who´s minimum homogenous weight is 142.

Homogenous weight enumerator: w(x)=1x^0+1176x^142+49x^144+896x^147+1960x^150+14x^168

The gray image is a linear code over GF(8) with n=168, k=4 and d=142.
This code was found by Heurico 1.16 in 0.0238 seconds.