The generator matrix

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

generates a code of length 51 over GR(16,4) who´s minimum homogenous weight is 142.

Homogenous weight enumerator: w(x)=1x^0+468x^142+636x^143+150x^144+1620x^146+1176x^147+213x^148+2280x^150+1236x^151+222x^152+1932x^154+1260x^155+216x^156+1560x^158+1296x^159+126x^160+1008x^162+492x^163+72x^164+348x^166+48x^167+12x^168+9x^176+3x^180

The gray image is a code over GF(4) with n=204, k=7 and d=142.
This code was found by Heurico 1.16 in 1.22 seconds.