Column 3 of triangle A152798; a(n) = A152798(n+3,3).

Terms

a(0) =1a(1) =1a(2) =4a(3) =10a(4) =29a(5) =93a(6) =310a(7) =1106a(8) =4205a(9) =16912a(10) =71858a(11) =321921a(12) =1516429a(13) =7493126a(14) =38758968a(15) =209453249a(16) =1180293354a(17) =6923457745a(18) =42206892713a(19) =267002169884