Number of one-sided triangular polyominoes (n-iamonds) with n cells; turning over not allowed, holes are allowed.

A006534

Number of one-sided triangular polyominoes (n-iamonds) with n cells; turning over not allowed, holes are allowed.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =4a(4) =6a(5) =19a(6) =43a(7) =120a(8) =307a(9) =866a(10) =2336a(11) =6588a(12) =18373a(13) =52119a(14) =147700a(15) =422016a(16) =1207477a(17) =3471067a(18) =9999135a(19) =28893560a(20) =83665729a(21) =242826187a(22) =706074369a(23) =2056870697a(24) =6001555275a(25) =17538335077a(26) =51323792789a(27) =150390053432a(28) =441210664337

External references