Number of staircase polygons of area n with 3 (staircase polygon) holes on square lattice (not allowing rotations).

A057416

Number of staircase polygons of area n with 3 (staircase polygon) holes on square lattice (not allowing rotations).

Terms

    a(0) =4a(1) =30a(2) =184a(3) =894a(4) =3885a(5) =15386a(6) =56956a(7) =199620a(8) =669702a(9) =2166462a(10) =6798186a(11) =20786496a(12) =62160079a(13) =182336358a(14) =525931258a(15) =1494726848a(16) =4192885357a(17) =11625457180a(18) =31899800729a(19) =86717361496a(20) =233754981005a(21) =625311996048

External references