Number of inequivalent ways to color vertices of a regular tetrahedron using <= n colors.

Terms

a(0) =0a(1) =1a(2) =5a(3) =15a(4) =36a(5) =75a(6) =141a(7) =245a(8) =400a(9) =621a(10) =925a(11) =1331a(12) =1860a(13) =2535a(14) =3381a(15) =4425a(16) =5696a(17) =7225a(18) =9045a(19) =11191a(20) =13700a(21) =16611a(22) =19965a(23) =23805a(24) =28176a(25) =33125a(26) =38701a(27) =44955a(28) =51940a(29) =59711