Triangular array formed from even elements to right of middle of rows of Pascal's triangle.

Terms

a(0) =4a(1) =10a(2) =6a(3) =56a(4) =28a(5) =8a(6) =126a(7) =84a(8) =36a(9) =210a(10) =120a(11) =10a(12) =462a(13) =330a(14) =792a(15) =220a(16) =66a(17) =12a(18) =1716a(19) =286a(20) =78a(21) =2002a(22) =364a(23) =14a(24) =11440a(25) =8008a(26) =4368a(27) =1820a(28) =560a(29) =120