Number of achiral rooted trees.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =15a(6) =26a(7) =45a(8) =71a(9) =110a(10) =168a(11) =247a(12) =351a(13) =503a(14) =700a(15) =944a(16) =1294a(17) =1719a(18) =2267a(19) =2961a(20) =3839a(21) =4891a(22) =6297a(23) =7891a(24) =9912a(25) =12347a(26) =15381a(27) =18784a(28) =23203a(29) =28138