The generator matrix

 1  1  1  1  1  1
 0  3  0  0  0  3
 0  0  3  0  0 3a+6
 0  0  0  3  0 3a+6
 0  0  0  0  3 6a+6

generates a code of length 6 over GR(81,9) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+120x^18+1120x^27+6840x^36+21840x^45+472392x^48+29128x^54

The gray image is a code over GF(9) with n=54, k=6 and d=18.
This code was found by Heurico 1.16 in 1.37 seconds.