A177473 Number of permutations of order n avoiding the consecutive pattern 12'1'2.

1, 1, 2, 6, 18, 61, 272, 1410, 8048, 51550, 372995, 2976679, 25686748, 239687103, 2419267562, 26194183096, 301838412516, 3692782460824, 47891164866100, 655887513203263, 9449915113835659, 142923476094740969, 2265214890150056647, 37539217881003574022, 649054317768293760078

Offset

0,3

Comments

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.

Links

Table of n, a(n) for n=0..24.

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

Crossrefs

Cf. A117156, A177470, A177471, A177472, A177475, A177476, A177477, A177478, A177479, A177480, A177481, A177482, A177483, A177484, A376694.

Sequence in context: A123639 A228448 A346490 * A177471 A303117 A150052

Adjacent sequences: A177470 A177471 A177472 * A177474 A177475 A177476

Keyword

nonn

Author

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

Extensions

Edited and terms a(0), a(10)-a(24) added by Max Alekseyev, Oct 01 2024

Status

approved