Number of n-node unlabeled rooted trees with thickening limbs.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =12a(7) =17a(8) =28a(9) =42a(10) =69a(11) =105a(12) =176a(13) =275a(14) =460a(15) =740a(16) =1244a(17) =2030a(18) =3440a(19) =5695a(20) =9688a(21) =16243a(22) =27758a(23) =46948a(24) =80610a(25) =137401a(26) =236796a(27) =406258a(28) =702720a(29) =1211954