A274970 Number of 2-stack pushall sortable permutations of length n.

1, 1, 2, 6, 24, 120, 698, 4393, 28551, 187403, 1231517, 8080058, 52905865, 345820994

Offset

0,3

Comments

A 2-stack pushall sortable permutation is one that can be sorted by two stacks in series by pushing all elements to the stacks before writing any element to the output.

A permutation of length n is 2-stack pushall sortable if and only if it can be sorted by a sequence of 3n operations represented by a pushall stack word of length 3n.

Links

Table of n, a(n) for n=0..13.

Adeline Pierrot and Dominique Rossin, 2-stack pushall sortable permutations, arXiv:1303.4376 [cs.DM], 2013.

Crossrefs

Cf. A263929 (permutations sortable with two stacks in series).

Cf. A274969 (pushall stack words of length 3n).

Sequence in context: A068200 A189847 A189284 * A177525 A177532 A242573

Adjacent sequences: A274967 A274968 A274969 * A274971 A274972 A274973

Keyword

nonn,more

Author

David Bevan, Jul 13 2016

Extensions

a(11)-a(13) from Bert Dobbelaere, Dec 26 2018

Status

approved