A094538 Number of ternary words of length n that are not "bifix-free".

0, 0, 3, 9, 33, 99, 315, 945, 2883, 8649, 26091, 78273, 235233, 705699, 2118339, 6355017, 19068729, 57206187, 171629595, 514888785, 1544699313, 4634097939, 13902392691, 41707178073, 125121830427, 375365491281

Offset

0,3

Links

Table of n, a(n) for n=0..25.

Formula

Equals 3^n - A019308(n).

Crossrefs

See A019308 and A003000 for much more information. Cf. A094539.

Sequence in context: A333770 A281973 A219557 * A343735 A037129 A148987

Adjacent sequences: A094535 A094536 A094537 * A094539 A094540 A094541

Keyword

nonn,easy

Author

N. J. A. Sloane, Jun 06 2004

Status

approved