Let D​{4​,7​,​9}, E​{4,6,7,8​} and F​{3​,​5,​6,​7,​9}.

Answer 1

D{4,7,9}, E{4,6,7,8}, G{3,5,6,7,9}, maybe H{3,4,5,6,7,8} I{2,3,4,5,6,7,9}...

1s term is 4,4,3,3,2,2,...

2nd term(s) are 7, 5,6,7, 4,5,6,7, 3,4,5,6,7, 2,3,4,5,6,7, ...

last term is 9, 8, 9, 8, ....