The generator matrix

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

generates a code of length 18 over GR(16,4) who´s minimum homogenous weight is 50.

Homogenous weight enumerator: w(x)=1x^0+216x^50+240x^51+24x^52+144x^54+36x^56+216x^58+144x^59+3x^64

The gray image is a code over GF(4) with n=72, k=5 and d=50.
This code was found by Heurico 1.16 in 0.016 seconds.