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

0,2

Links

Table of n, a(n) for n=0..38.

Eric Weisstein's World of Mathematics, Squarefree Word

Formula

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

Crossrefs

Cf. A088952, A007089.

Sequence in context: A353188 A147620 A195746 * A281612 A349050 A025034

Adjacent sequences: A088950 A088951 A088952 * A088954 A088955 A088956

Keyword

nonn

Author

Reinhard Zumkeller, Oct 25 2003

Status

approved