One half of the even entries of A033317.

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =1a(5) =90a(6) =2a(7) =4a(8) =2a(9) =1a(10) =6a(11) =21a(12) =5a(13) =12a(14) =910a(15) =1a(16) =2a(17) =3a(18) =6a(19) =3a(20) =2a(21) =160a(22) =1a(23) =15a(24) =12a(25) =1794a(26) =7a(27) =45a(28) =4550a(29) =33