Number of generalized polyforms on the snub square tiling with n cells.

Terms

a(0) =1a(1) =2a(2) =2a(3) =4a(4) =10a(5) =28a(6) =79a(7) =235a(8) =720a(9) =2254a(10) =7146a(11) =22927a(12) =74137a(13) =241461a(14) =790838a(15) =2603210a(16) =8604861a(17) =28549166a(18) =95027832a(19) =317229779a(20) =1061764660a(21) =3562113987a(22) =11976146355