A088953 Number of numbers that are ternary squarefree words of length n.

1, 3, 4, 8, 12, 20, 28, 40, 52, 72, 96, 136, 176, 228, 304, 412, 532, 696, 928, 1220, 1592, 2120, 2764, 3612, 4688, 6132, 7928, 10324, 13480, 17616, 22948, 29908, 38964, 50748, 66184, 86344, 112364, 146344, 190500

Offset: 0

Author

Reinhard Zumkeller, Oct 25 2003

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Squarefree Word

Crossrefs

Cf. A088952, A007089.

Formula

a(n) = A006156(n)*2/3 for n>1 [Corrected by Rémy Sigrist, Aug 19 2020].