Number of diagonal dissections of an n-gon into 4 regions.

Terms

a(0) =0a(1) =14a(2) =84a(3) =300a(4) =825a(5) =1925a(6) =4004a(7) =7644a(8) =13650a(9) =23100a(10) =37400a(11) =58344a(12) =88179a(13) =129675a(14) =186200a(15) =261800a(16) =361284a(17) =490314a(18) =655500a(19) =864500a(20) =1126125a(21) =1450449a(22) =1848924a(23) =2334500a(24) =2921750a(25) =3627000a(26) =4468464a(27) =5466384a(28) =6643175a(29) =8023575