Number of achiral hexagonal polyominoes with 3n cells and threefold rotational symmetry centered at a vertex.

A350243

Number of achiral hexagonal polyominoes with 3n cells and threefold rotational symmetry centered at a vertex.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =9a(5) =19a(6) =39a(7) =82a(8) =171a(9) =368a(10) =773a(11) =1678a(12) =3559a(13) =7776a(14) =16601a(15) =36470a(16) =78295a(17) =172720a(18) =372440a(19) =824512a(20) =1784463a(21) =3961869a(22) =8601227a(23) =19143685a(24) =41671452a(25) =92944943a(26) =202787164a(27) =453138925a(28) =990656774a(29) =2217280465

External references