Number of indecomposable permutations sortable using two parallel stacks.

A215252

Number of indecomposable permutations sortable using two parallel stacks.

Terms

    a(0) =0a(1) =1a(2) =1a(3) =3a(4) =12a(5) =56a(6) =289a(7) =1602a(8) =9367a(9) =57075a(10) =359346a(11) =2323416a(12) =15356446a(13) =103389175a(14) =707107627a(15) =4901988047a(16) =34384943850a(17) =243694702311

External references