a(n) = A029571(n) / 6.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =5a(6) =30a(7) =210a(8) =1470a(9) =13230a(10) =132300a(11) =1455300a(12) =17671500a(13) =229729500a(14) =3216213000a(15) =48243195000a(16) =771323553000