Twice Pascal's triangle A007318: T(n,k) = 2*C(n,k).

Terms

a(0) =2a(1) =2a(2) =2a(3) =2a(4) =4a(5) =2a(6) =2a(7) =6a(8) =6a(9) =2a(10) =2a(11) =8a(12) =12a(13) =8a(14) =2a(15) =2a(16) =10a(17) =20a(18) =20a(19) =10a(20) =2a(21) =2a(22) =12a(23) =30a(24) =40a(25) =30a(26) =12a(27) =2a(28) =2a(29) =14