Number of unlabeled vertically indecomposable modular lattices on n nodes.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =2a(6) =3a(7) =7a(8) =12a(9) =28a(10) =54a(11) =127a(12) =266a(13) =614a(14) =1356a(15) =3134a(16) =7091a(17) =16482a(18) =37929a(19) =88622a(20) =206295a(21) =484445a(22) =1136897a(23) =2682451a(24) =6333249a(25) =15005945a(26) =35595805a(27) =84649515a(28) =201560350a(29) =480845007