generators.regularTreeGrammar("table sequences (optimized)"):
(
  { A, B, C, D },
  { tab1:1, tab2:1, tab3:1, tab4:1, e:0 },
  {
    A -> tab1[A], A -> tab1[B],
    B -> tab2[C],
    C -> tab3[C], C -> D,
    D -> tab4[e]
  },
  A
)