Principal diagonal of the convolution array A213590.

Terms

a(0) =1a(1) =6a(2) =35a(3) =138a(4) =488a(5) =1564a(6) =4733a(7) =13734a(8) =38711a(9) =106846a(10) =290496a(11) =781264a(12) =2084753a(13) =5531846a(14) =14619811a(15) =38527834a(16) =101328712a(17) =266119228a(18) =698218525a(19) =1830665830a(20) =4797572551a(21) =12568780126a(22) =32920653120a(23) =86214096768a(24) =225758326273