Triangle of coefficients of x^2 in the Neumann polynomials.

Terms

a(0) =1a(1) =1a(2) =4a(3) =1a(4) =24a(5) =3a(6) =192a(7) =16a(8) =1a(9) =1920a(10) =120a(11) =5a(12) =23040a(13) =1152a(14) =36a(15) =1a(16) =322560a(17) =13440a(18) =336a(19) =7a(20) =5160960a(21) =184320a(22) =3840a(23) =64a(24) =1a(25) =92897280a(26) =2903040a(27) =51840a(28) =720a(29) =9