Number of 6-ary search trees on n keys.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =6a(7) =21a(8) =56a(9) =126a(10) =252a(11) =492a(12) =1062a(13) =2667a(14) =7252a(15) =19509a(16) =49824a(17) =121019a(18) =286974a(19) =687384a(20) =1702308a(21) =4357383a(22) =11322408a(23) =29307458a(24) =74897808a(25) =189349041a(26) =477491356a(27) =1211349276a(28) =3103673406a(29) =8017385416