The generator matrix

 1  0  1  1  1  0  1  1  0  1  1  2  1  1  0  1  1  2  0  1  1
 0  1  1  0  1  1  0  3  1  2  1  1  0  3  1  2  0  2  2  2  0
 0  0  2  0  0  2  2  0  0  2  2  2  2  0  2  2  2  2  2  0  0
 0  0  0  2  0  2  2  2  2  0  2  0  0  0  0  2  2  0  2  2  0
 0  0  0  0  2  2  2  2  0  2  0  2  2  2  2  2  0  0  0  0  2

generates a code of length 21 over Z4 who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+31x^18+36x^20+29x^22+25x^24+3x^26+2x^28+1x^38

The gray image is a code over GF(2) with n=42, k=7 and d=18.
This code was found by Heurico 1.16 in 0.00252 seconds.