Duplicate of A027611.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =12a(5) =10a(6) =20a(7) =35a(8) =280a(9) =252a(10) =2520a(11) =2310a(12) =27720a(13) =25740a(14) =24024a(15) =45045a(16) =720720