Total number of nodes in all planted trees on n nodes.

Terms

a(0) =0a(1) =2a(2) =3a(3) =8a(4) =20a(5) =54a(6) =140a(7) =384a(8) =1035a(9) =2860a(10) =7909a(11) =22104a(12) =61958a(13) =174804a(14) =494595a(15) =1404976a(16) =4001477a(17) =11427246a(18) =32702021a(19) =93773520a(20) =269350788a(21) =774880304a(22) =2232269163a(23) =6438788520a(24) =18593124600a(25) =53746540770a(26) =155510185770a(27) =450344561212