The generator matrix

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

generates a code of length 21 over Z2[X]/(X^3) who´s minimum homogenous weight is 16.

Homogenous weight enumerator: w(x)=1x^0+45x^16+129x^20+256x^21+50x^24+30x^28+1x^36

The gray image is a linear code over GF(2) with n=84, k=9 and d=32.
This code was found by Heurico 1.16 in 0.0075 seconds.