The generator matrix

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

generates a code of length 71 over GR(16,4) who´s minimum homogenous weight is 196.

Homogenous weight enumerator: w(x)=1x^0+396x^196+252x^197+180x^198+600x^199+2190x^200+948x^201+708x^202+1224x^203+3672x^204+1440x^205+744x^206+1932x^207+5406x^208+2064x^209+1164x^210+2280x^211+7089x^212+2484x^213+1188x^214+2364x^215+7332x^216+2532x^217+924x^218+2232x^219+5175x^220+1608x^221+768x^222+1188x^223+2673x^224+792x^225+372x^226+408x^227+660x^228+168x^229+96x^230+60x^231+150x^232+18x^236+15x^240+18x^244+6x^248+9x^252+3x^256+3x^260

The gray image is a code over GF(4) with n=284, k=8 and d=196.
This code was found by Heurico 1.16 in 21.1 seconds.