The generator matrix

 1  0  0  1  1  1  1  1  1  1 2a+2  0  1  1 2a  1  1  1  1  1  1
 0  1  0  1  a  0 3a+3 2a+2  1 2a+3  1  1 2a  3  1 2a 3a+1  2 a+1 3a a+1
 0  0  1 3a+3  a  a  1  3  1 3a 2a+1  a  0 a+3 3a+1  3 3a a+3 a+2 a+2 a+1
 0  0  0  2  0 2a 2a+2 2a+2 2a  2  0 2a+2 2a+2  0 2a+2  0 2a 2a 2a+2  2  2

generates a code of length 21 over GR(16,4) who´s minimum homogenous weight is 54.

Homogenous weight enumerator: w(x)=1x^0+360x^54+1239x^56+1236x^58+1860x^60+2772x^62+3510x^64+2748x^66+2028x^68+564x^70+57x^72+9x^80

The gray image is a code over GF(4) with n=84, k=7 and d=54.
This code was found by Heurico 1.16 in 6.12 seconds.