Number of self-avoiding polygons of area n with any number of (self-avoiding polygon) holes on square lattice (not allowing rotations).

A057409

Number of self-avoiding polygons of area n with any number of (self-avoiding polygon) holes on square lattice (not allowing rotations).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =19a(4) =63a(5) =216a(6) =756a(7) =2685a(8) =9650a(9) =35018a(10) =128084a(11) =471623a(12) =1746492a(13) =6499356a(14) =24290272a(15) =91123171a(16) =342984175a(17) =1294829776a(18) =4901319978a(19) =18597856445a(20) =70723784744a(21) =269486503694

External references