The generator matrix

 1  0  0  1  1  1  X X^2+X  0 X^2  1  1  1  1  1  1  1  1  1  1  1
 0  1  0 X^2 X^2+1  1  1  1  1  X  X X+1 X^2+X  X X^2+X+1 X+1 X^2+X X^2+X+1 X^2  0  0
 0  0  1 X^2+X+1 X+1 X^2 X^2+1 X+1 X^2+X  1 X^2+X+1 X^2 X^2+1 X^2+X X+1  1  0  X X^2+X X^2+X X^2

generates a code of length 21 over Z2[X]/(X^3) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+18x^18+116x^19+125x^20+92x^21+38x^22+46x^23+26x^24+32x^25+15x^26+2x^27+1x^30

The gray image is a linear code over GF(2) with n=84, k=9 and d=36.
This code was found by Heurico 1.16 in 0.00428 seconds.