The generator matrix 1 0 0 0 1 1 1 0 1 1 0 1 0 0 0 1 1 1 0 0 0 0 1 0 1 1 0 1 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 0 X 0 0 0 0 X 0 0 0 0 0 X 0 0 0 X 0 0 0 0 0 0 X 0 0 X 0 0 0 0 0 0 0 X 0 X 0 0 0 0 0 0 0 0 X X generates a code of length 10 over Z2[X]/(X^2) who´s minimum homogenous weight is 4. Homogenous weight enumerator: w(x)=1x^0+101x^4+560x^6+1946x^8+2976x^10+1946x^12+560x^14+101x^16+1x^20 The gray image is a linear code over GF(2) with n=20, k=13 and d=4. As d=4 is an upper bound for linear (20,13,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 13. This code was found by Heurico 1.16 in 0.124 seconds.