How to express the desired sequence through nth-of-type?

Question

css

There is a kind of list that I would like to implement through nth-of-type, without resorting to modifiers and javascript.

Basically I need to roll flex-basis 1 into: 2, 3, 6, 7, 10, 11 etc.
flex-basis 2 into: 1, 4, 5, 8, 9, 12, 13 etc.
UPD who seeks, he will always find.
atmpl.ru/index/generator_nth_child_bootstrap Let's summarize
what worked:

elem(row){
    @extend %row;
    @extend %row--wrap;
  }
  elem(item){
    padding-bottom: 30px;
    width: 100%;
    &:nth-of-type(2n+1){
      padding-right: 40px;
    }
    &:nth-of-type(4n+1), &:nth-of-type(4n+4){
      max-width: 560px;
    }
    &:nth-of-type(4n-2), &:nth-of-type(4n-1){
      max-width: 1120px;
    }
  }