Number of squarefree words of length 7 in an (n+1)-ary alphabet.

Terms

a(0) =0a(1) =60a(2) =1848a(3) =15960a(4) =80040a(5) =292740a(6) =868560a(7) =2218608a(8) =5062320a(9) =10575180a(10) =20577480a(11) =37769160a(12) =66015768a(13) =110690580a(14) =179077920a(15) =280842720a(16) =428571360a(17) =638388828a(18) =930657240a(19) =1330760760a(20) =1869981960a(21) =2586474660a(22) =3526338288a(23) =4744798800