The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1
 0  1  1  a 7a+7 8a+4 3a+5 8a+5 8a a+5  0 a+5 8a 8a+5 8a+4  1  a 7a+7 8a+5  0  3
 0  0 3a+6  0 3a+6  3 6a+6 6a+6  6 3a 3a+6 3a  3 3a  3  3 6a+6  6  6 6a+3 6a
 0  0  0  3 3a+6 3a+6  3 3a  3 3a+3 6a 6a+6 6a 6a+3  0 6a+6 3a+3 3a+6 6a+3 3a+6 6a+3

generates a code of length 21 over GR(81,9) who´s minimum homogenous weight is 144.

Homogenous weight enumerator: w(x)=1x^0+584x^144+216x^145+3888x^152+2856x^153+3240x^154+11664x^160+62208x^161+14904x^162+16200x^163+93312x^169+248832x^170+38536x^171+32832x^172+1632x^180+536x^189

The gray image is a code over GF(9) with n=189, k=6 and d=144.
This code was found by Heurico 1.16 in 9.08 seconds.