Fourth column of PE^2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =8a(5) =60a(6) =440a(7) =3290a(8) =25424a(9) =204120a(10) =1705680a(11) =14836470a(12) =134240040a(13) =1262060228a(14) =12313382536a(15) =124509169330