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A088953
Number of numbers that are ternary squarefree words of length n.
1
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
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
Sequence in context: A353188 A147620 A195746 * A281612 A349050 A025034
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 25 2003
STATUS
approved