a(n) = (A097406(n) - 1)/n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =1a(4) =6a(5) =0a(6) =18a(7) =2a(8) =8a(9) =1a(10) =8a(11) =1a(12) =630a(13) =3a(14) =10a(15) =16a(16) =7710a(17) =1a(18) =27594a(19) =2a(20) =16a(21) =31a(22) =7760a(23) =10a(24) =72a(25) =105a(26) =9728a(27) =4a(28) =72a(29) =11