The generator matrix

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

generates a code of length 21 over Z7[X]/(X^2) who´s minimum homogenous weight is 114.

Homogenous weight enumerator: w(x)=1x^0+126x^114+2898x^115+5796x^116+138x^119+294x^120+1512x^121+14490x^122+15456x^123+14544x^126+1764x^127+4536x^128+29946x^129+26082x^130+18x^133+6x^140+42x^147

The gray image is a linear code over GF(7) with n=147, k=6 and d=114.
This code was found by Heurico 1.16 in 1.12 seconds.