Principal diagonal of the convolution array A213584.

Terms

a(0) =1a(1) =7a(2) =22a(3) =54a(4) =116a(5) =232a(6) =443a(7) =821a(8) =1490a(9) =2664a(10) =4710a(11) =8256a(12) =14373a(13) =24883a(14) =42878a(15) =73594a(16) =125880a(17) =214664a(18) =365087a(19) =619425a(20) =1048666a(21) =1771852a(22) =2988362a(23) =5031744a(24) =8459401a(25) =14201887a(26) =23811238a(27) =39873726a(28) =66695420a(29) =111440104