The generator matrix

 1  0  1
 0  1 36

generates a code of length 3 over Z49 who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+126x^12+18x^14+1470x^18+756x^19+30x^21

The gray image is a code over GF(7) with n=21, k=4 and d=12.
This code was found by Heurico 1.16 in 4.98e-005 seconds.