Column 4 of triangle A117418.

Terms

a(0) =1a(1) =5a(2) =20a(3) =79a(4) =322a(5) =1385a(6) =6293a(7) =30152a(8) =151842a(9) =801220a(10) =4414013a(11) =25314411a(12) =150707813a(13) =929456660a(14) =5924776551a(15) =38954031366a(16) =263667692262