Dirichlet convolution of Catalan numbers (1,2,5,14...) with themselves.

Terms

a(0) =1a(1) =4a(2) =10a(3) =32a(4) =84a(5) =284a(6) =858a(7) =2916a(8) =9749a(9) =33760a(10) =117572a(11) =416692a(12) =1485800a(13) =5350596a(14) =19390110a(15) =70721256a(16) =259289580a(17) =955298168a(18) =3534526380a(19) =13128309200a(20) =48932538330a(21) =182965362424a(22) =686119227300