T(n,n-1), array T as in A047120.

Terms

a(0) =1a(1) =1a(2) =4a(3) =16a(4) =58a(5) =215a(6) =806a(7) =3051a(8) =11602a(9) =44307a(10) =169840a(11) =653204a(12) =2519314a(13) =9740350a(14) =37739300a(15) =146498531a(16) =569642584a(17) =2218322463a(18) =8650367796a(19) =33773500347a(20) =132008143328a(21) =516495270723