Linear OA(5⁷¹, 821, F₅, 20) (dual of [821, 750, 21]-code), using 749 step VarÅ¡amov–Edel lengthening with (r_i) = (5, 2, 2, 1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 4 times 0, 1, 4 times 0, 1, 5 times 0, 1, 5 times 0, 1, 6 times 0, 1, 7 times 0, 1, 7 times 0, 1, 8 times 0, 1, 9 times 0, 1, 10 times 0, 1, 12 times 0, 1, 12 times 0, 1, 14 times 0, 1, 15 times 0, 1, 16 times 0, 1, 18 times 0, 1, 20 times 0, 1, 22 times 0, 1, 24 times 0, 1, 26 times 0, 1, 29 times 0, 1, 31 times 0, 1, 35 times 0, 1, 37 times 0, 1, 41 times 0, 1, 45 times 0, 1, 49 times 0, 1, 54 times 0, 1, 59 times 0, 1, 64 times 0) based on linear OA(5²⁰, 21, F₅, 20) (dual of [21, 1, 21]-code or 21-arc in PG(19,5)), using

• dual of repetition code with length 21 [i]