The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  0  1  1
 0  1  1  3 5X+2  6 5X+4  5  0 5X+1  3 5X+2  6 5X+4  5  1  5 5X+2  1 5X+1  0
 0  0 5X  0 5X  X 5X  X 6X 2X  X 6X  0  0 6X 2X 3X 4X 4X 3X  0
 0  0  0  X 4X 4X 3X 6X  0 6X  X 6X 5X 4X 3X 3X 6X 3X 4X  0  0

generates a code of length 21 over Z7[X]/(X^2) who´s minimum homogenous weight is 105.

Homogenous weight enumerator: w(x)=1x^0+126x^105+462x^108+450x^112+882x^114+4788x^115+360x^119+10584x^121+19908x^122+444x^126+31752x^128+46872x^129+492x^133+420x^140+108x^147

The gray image is a linear code over GF(7) with n=147, k=6 and d=105.
This code was found by Heurico 1.16 in 1.47 seconds.