Number of symmetry classes of 3-eared triangulations of an n-gon.

Terms

a(0) =0a(1) =1a(2) =1a(3) =5a(4) =14a(5) =42a(6) =112a(7) =304a(8) =768a(9) =1928a(10) =4696a(11) =11280a(12) =26624a(13) =62160a(14) =143360a(15) =327744a(16) =742752a(17) =1671296a(18) =3735552a(19) =8301504a(20) =18350080a(21) =40370688a(22) =88429952a(23) =192939008a(24) =419430400a(25) =908768000a(26) =1962934272a(27) =4227862528a(28) =9082066432a(29) =19461578752