a(n) is the number of unlabeled, graded rank-3 lattices with n elements.

A300221

a(n) is the number of unlabeled, graded rank-3 lattices with n elements.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =4a(6) =8a(7) =18a(8) =38a(9) =88a(10) =210a(11) =528a(12) =1396a(13) =3946a(14) =11896a(15) =38644a(16) =135790a(17) =518645a(18) =2160112a(19) =9832013a(20) =48945468a(21) =266458643

External references