Third-from-right diagonal of triangle A121207.

Terms

a(0) =1a(1) =1a(2) =4a(3) =14a(4) =54a(5) =233a(6) =1101a(7) =5625a(8) =30846a(9) =180474a(10) =1120666a(11) =7352471a(12) =50772653a(13) =367819093a(14) =2787354668a(15) =22039186530a(16) =181408823710