Number of unlabeled (and unrooted) trees on n nodes having a centroid.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =3a(6) =3a(7) =11a(8) =13a(9) =47a(10) =61a(11) =235a(12) =341a(13) =1301a(14) =1983a(15) =7741a(16) =12650a(17) =48629a(18) =82826a(19) =317955a(20) =564225a(21) =2144505a(22) =3926353a(23) =14828074a(24) =27940136a(25) =104636890a(26) =201837109a(27) =751065460a(28) =1479817181a(29) =5469566585