Number of hierarchical orderings ("societies") of n unlabeled elements ("individuals") with at least two occupied levels.

A110045

Number of hierarchical orderings ("societies") of n unlabeled elements ("individuals") with at least two occupied levels.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =3a(4) =8a(5) =18a(6) =45a(7) =102a(8) =245a(9) =565a(10) =1324a(11) =3049a(12) =7066a(13) =16199a(14) =37187a(15) =84887a(16) =193532a(17) =439600a(18) =996818a(19) =2253941a(20) =5086980a(21) =11454778a(22) =25746467a(23) =57756522a(24) =129342179a(25) =289153474a(26) =645399011a(27) =1438308839a(28) =3200671082a(29) =7112360474

External references