Number of semi-lone-child-avoiding rooted trees with at most one distinct non-leaf branch directly under any vertex.

A331933

Number of semi-lone-child-avoiding rooted trees with at most one distinct non-leaf branch directly under any vertex.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =6a(6) =12a(7) =18a(8) =33a(9) =52a(10) =90a(11) =142a(12) =242a(13) =384a(14) =639a(15) =1028a(16) =1688a(17) =2716a(18) =4445a(19) =7161a(20) =11665a(21) =18839a(22) =30595a(23) =49434a(24) =80199a(25) =129637a(26) =210079a(27) =339750a(28) =550228a(29) =889978

External references