The generator matrix

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

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

Homogenous weight enumerator: w(x)=1x^0+76x^18+69x^20+54x^22+23x^24+24x^26+3x^28+6x^30

The gray image is a code over GF(2) with n=42, k=8 and d=18.
This code was found by Heurico 1.16 in 0.0607 seconds.