Column 3 of triangle in A059317 (the Pascal "Rhombus").

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =19a(6) =70a(7) =261a(8) =914a(9) =3177a(10) =10816a(11) =36566a(12) =122552a(13) =408840a(14) =1358032a(15) =4497995a(16) =14862112a(17) =49019688a(18) =161449208a(19) =531152855a(20) =1745892452a(21) =5734722698a(22) =18826352472a(23) =61777432510a(24) =202648614072a(25) =664569581090