Number of rooted trees where each node has at most 4 children.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =9a(6) =19a(7) =45a(8) =106a(9) =260a(10) =643a(11) =1624a(12) =4138a(13) =10683a(14) =27790a(15) =72917a(16) =192548a(17) =511624a(18) =1366424a(19) =3666930a(20) =9881527a(21) =26730495a(22) =72556208a(23) =197562840a(24) =539479354a(25) =1477016717a(26) =4053631757a(27) =11149957667a(28) =30732671572a(29) =84871652538