Total number of nodes in all trees with n nodes.

Terms

a(0) =1a(1) =2a(2) =3a(3) =8a(4) =15a(5) =36a(6) =77a(7) =184a(8) =423a(9) =1060a(10) =2585a(11) =6612a(12) =16913a(13) =44226a(14) =116115a(15) =309120a(16) =826693a(17) =2229606a(18) =6041145a(19) =16461300a(20) =45034605a(21) =123722632a(22) =341045702a(23) =943197528a(24) =2615922250a(25) =7274629700a(26) =20278767420a(27) =56656404896a(28) =158617430965a(29) =444926154060