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

Author

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

Keywords

• nonn

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

• 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.

Extensions

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