Number of unrooted triangulations with reflection symmetry of a pentagon with n internal nodes.

A005506

Number of unrooted triangulations with reflection symmetry of a pentagon with n internal nodes.

Terms

    a(0) =1a(1) =3a(2) =7a(3) =19a(4) =57a(5) =176a(6) =557a(7) =1806a(8) =5954a(9) =19897a(10) =67235a(11) =229366a(12) =788688a(13) =2730810a(14) =9512107a(15) =33309444a(16) =117190184a(17) =414039578a(18) =1468349782a(19) =5225201321a(20) =18651958885a(21) =66769742002a(22) =239643164237a(23) =862168692562

External references