Principal diagonal of the convolution array A213747.

Terms

a(0) =1a(1) =16a(2) =125a(3) =758a(4) =4071a(5) =20424a(6) =98185a(7) =458506a(8) =2096651a(9) =9436172a(10) =41941005a(11) =184545294a(12) =805298191a(13) =3489644560a(14) =15032352785a(15) =64424443922a(16) =274877775891