Total number of fixed points in rooted trees with n nodes.

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =28a(5) =78a(6) =213a(7) =598a(8) =1670a(9) =4723a(10) =13356a(11) =37986a(12) =108193a(13) =309169a(14) =884923a(15) =2538369a(16) =7292170a(17) =20982220a(18) =60451567a(19) =174385063a(20) =503600439a(21) =1455827279a(22) =4212464112a(23) =12199373350a(24) =35357580112a(25) =102552754000a(26) =297651592188a(27) =864460682777