C(21,3,2) <=70

Method of construction: simple construction: induced on c(22,4,3) covering

10 12 21
10 13 16
10 14 17
 1 10 20
 1 11 12
11 13 14
12 15 20
 1 13 19
 1 14 15
14 18 19
15 17 21
 1 16 17
16 18 21
19 20 21
 2 11 21
 2 12 13
 2 14 20
 2 15 16
 2 17 18
 2  3  5
 1  2  4
 2  6 19
 2  7  8
 2  9 10
 3 10 15
 3 11 16
 3 12 14
 3 17 19
 3 18 20
 1  3 21
 3  4 13
 3  6  8
 3  7  9
 4 10 19
 4 11 20
 4 15 18
 4  5 17
 4  6 21
 4  7 14
 4  8 16
 4  9 12
 5 11 19
 5 12 16
 5 13 20
 1  5 18
 5  6 10
 5  7 21
 5  8 14
 5  9 15
 6 11 17
 6 12 18
 6 13 15
 6 14 16
 1  6  7
 6  9 20
 7 10 11
 7 12 17
 7 13 18
 7 15 19
 7 16 20
 8 10 18
 8 11 15
 8 12 19
 8 13 21
 8 17 20
 1  8  9
 9 11 18
 9 13 17
 9 14 21
 9 16 19