A337526 Number of length n permutations that are sorted to the identity by a consecutive-213-avoiding stack followed by a classical-21-avoiding stack.

1, 2, 5, 15, 50, 180, 686, 2731

Offset

1,2

Links

Table of n, a(n) for n=1..8.

C. Defant and K. Zheng, Stack-Sorting with Consecutive-Pattern-Avoiding Stacks, arXiv:2008.12297 [math.CO], 2020.

Example

For n = 3, the permutations 123, 213, 231, 312, and 321 are correctly sorted to the identity while the permutation 132 is not.

Crossrefs

Cf. A000108, A001006, A002026, A011782, A202062, A294790.

Sequence in context: A007853 A337522 A149952 * A346661 A060049 A107590

Adjacent sequences: A337523 A337524 A337525 * A337527 A337528 A337529

Keyword

nonn,more

Author

Kai Zheng, Aug 30 2020

Status

approved