One half of odd-numbered entries of even-numbered rows of Pascal's triangle A007318.

Terms

a(0) =1a(1) =2a(2) =2a(3) =3a(4) =10a(5) =3a(6) =4a(7) =28a(8) =28a(9) =4a(10) =5a(11) =60a(12) =126a(13) =60a(14) =5a(15) =6a(16) =110a(17) =396a(18) =396a(19) =110a(20) =6a(21) =7a(22) =182a(23) =1001a(24) =1716a(25) =1001a(26) =182a(27) =7a(28) =8a(29) =280