Principal diagonal of the convolution array A213555.

Terms

a(0) =1a(1) =19a(2) =118a(3) =446a(4) =1271a(5) =3017a(6) =6300a(7) =11964a(8) =21117a(9) =35167a(10) =55858a(11) =85306a(12) =126035a(13) =181013a(14) =253688a(15) =348024a(16) =468537a(17) =620331a(18) =809134a(19) =1041334a(20) =1324015a(21) =1664993a(22) =2072852a(23) =2556980a(24) =3127605a(25) =3795831a(26) =4573674a(27) =5474098a(28) =6511051a(29) =7699501