Main diagonal of A323212.

Terms

a(0) =1a(1) =1a(2) =7a(3) =56a(4) =477a(5) =4180a(6) =37401a(7) =339184a(8) =3107583a(9) =28691938a(10) =266537777a(11) =2488340790a(12) =23326071990a(13) =219416722056