Number of permutations sortable using two parallel stacks.

A216040

Number of permutations sortable using two parallel stacks.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =23a(5) =103a(6) =513a(7) =2760a(8) =15741a(9) =93944a(10) =581303a(11) =3704045a(12) =24180340a(13) =161082639a(14) =1091681427a(15) =7508269793a(16) =52302594344a(17) =368422746908

External references