a(n) is the number of squares in the n-th ring (n >= 0) of the Poincaré diagram of the order-5 square tiling of the hyperbolic plane (Schläfli symbol {4,5}).

A390190

a(n) is the number of squares in the n-th ring (n >= 0) of the Poincaré diagram of the order-5 square tiling of the hyperbolic plane (Schläfli symbol {4,5}).

Terms

    a(0) =5a(1) =25a(2) =95a(3) =355a(4) =1325a(5) =4945a(6) =18455a(7) =68875a(8) =257045a(9) =959305a(10) =3580175a(11) =13361395a(12) =49865405a(13) =186100225a(14) =694535495a(15) =2592041755a(16) =9673631525a(17) =36102484345a(18) =134736305855a(19) =502842739075

External references