Third column of PE^3.

Terms

a(0) =0a(1) =0a(2) =1a(3) =9a(4) =72a(5) =570a(6) =4635a(7) =39186a(8) =345828a(9) =3188268a(10) =30684150a(11) =307870365a(12) =3215425554a(13) =34899450768a(14) =393015753039