A177473 Avoiding the pattern 12'1'2.To avoid 12'1'2 means not to have four consecutive letters such that the first one is less than the fourth letter and the second letter is larger than the third one.

1, 2, 6, 18, 61, 272, 1410, 8048, 51550

Offset

1,2

Links

Table of n, a(n) for n=1..9.

S. Kitaev, Introduction to partially ordered patterns, Discrete Applied Mathematics 155 (2007), 929-944.

Crossrefs

Sequence in context: A123639 A228448 A346490 * A177471 A303117 A150052

Adjacent sequences: A177470 A177471 A177472 * A177474 A177475 A177476

Keyword

nonn,more

Author

Signy Olafsdottir (signy06(AT)ru.is), May 09 2010

Status

approved