Linear OA(2²⁴⁹, 613, F₂, 52) (dual of [613, 364, 53]-code), using 60 step VarÅ¡amov–Edel lengthening with (r_i) = (7, 3, 2, 2, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 4 times 0, 1, 4 times 0, 1, 4 times 0, 1, 5 times 0, 1, 5 times 0) based on linear OA(2²¹⁷, 521, F₂, 52) (dual of [521, 304, 53]-code), using

• 1 times truncation [i] based on linear OA(2²¹⁸, 522, F₂, 53) (dual of [522, 304, 54]-code), using
  • construction X applied to C_e(52) ⊂ C_e(50) [i] based on
    1. linear OA(2²¹⁷, 512, F₂, 53) (dual of [512, 295, 54]-code), using an extension C_e(52) of the primitive narrow-sense BCH-code C(I) with length 511 = 2⁹−1, defining interval I = [1,52], and designed minimum distance d ≥ |I|+1 = 53 [i]
    2. linear OA(2²⁰⁸, 512, F₂, 51) (dual of [512, 304, 52]-code), using an extension C_e(50) of the primitive narrow-sense BCH-code C(I) with length 511 = 2⁹−1, defining interval I = [1,50], and designed minimum distance d ≥ |I|+1 = 51 [i]
    3. linear OA(2¹, 10, F₂, 1) (dual of [10, 9, 2]-code), using
       • discarding factors / shortening the dual code based on linear OA(2¹, s, F₂, 1) (dual of [s, s−1, 2]-code) for arbitrarily large s, using
         • parity-check code [i]