Number of staircase polygons of perimeter 2n with any number of (staircase polygon) holes on square lattice (not allowing rotations).

A057413

Number of staircase polygons of perimeter 2n with any number of (staircase polygon) holes on square lattice (not allowing rotations).

Terms

    a(0) =1a(1) =2a(2) =5a(3) =14a(4) =42a(5) =132a(6) =430a(7) =1442a(8) =4956a(9) =17400a(10) =62251a(11) =226506a(12) =836911a(13) =3136182a(14) =11906908a(15) =45761338a(16) =177903128a(17) =699167112a(18) =2776219871a(19) =11132523840a(20) =45062497156a(21) =184057276510a(22) =758328417263

External references