Number of solid standard Young tableaux of shape [[n,n-1],[1]].

Terms

a(0) =1a(1) =6a(2) =25a(3) =98a(4) =378a(5) =1452a(6) =5577a(7) =21450a(8) =82654a(9) =319124a(10) =1234506a(11) =4784276a(12) =18572500a(13) =72209880a(14) =281150505a(15) =1096087770a(16) =4278278070a(17) =16717354500a(18) =65388738030a(19) =256000696380