Number of trees on n nodes with forbidden limbs.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =6a(7) =10a(8) =21a(9) =45a(10) =100a(11) =223a(12) =522a(13) =1234a(14) =2997a(15) =7344a(16) =18325a(17) =46098a(18) =117340a(19) =300935a(20) =778249a(21) =2025542a(22) =5305684a(23) =13972364a(24) =36985033a(25) =98344160a(26) =262612283a(27) =703971120a(28) =1893895747a(29) =5112056798