The generator matrix

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

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+147x^18+108x^19+256x^20+72x^21+238x^22+48x^23+77x^24+24x^25+47x^26+4x^27+2x^28

The gray image is a linear code over GF(2) with n=84, k=10 and d=36.
This code was found by Heurico 1.16 in 0.0145 seconds.