A215252 Number of indecomposable permutations sortable using two parallel stacks.

0, 1, 1, 3, 12, 56, 289, 1602, 9367, 57075, 359346, 2323416, 15356446, 103389175, 707107627, 4901988047, 34384943850, 243694702311, 1742953208739, 12567593026554, 91280392585747, 667341975412356, 4907899368783645, 36289929612761691, 269660272111724536, 2012845416966620068, 15087243969226496324, 113521159338891300347, 857211201390859034536

Offset

0,4

Comments

Suggested by Peter Doyle in an email message, Sep 04 2012

Links

N. J. A. Sloane, Table of n, a(n) for n = 0..100

Formula

INVERTi transform of A216040.

Crossrefs

Cf. A003319, A216040, A182216, A215257.

Sequence in context: A301418 A224922 A303925 * A284712 A284713 A180256

Adjacent sequences: A215249 A215250 A215251 * A215253 A215254 A215255

Keyword

nonn

Author

N. J. A. Sloane, Sep 07 2012. a(0)=0 added by N. J. A. Sloane, Sep 12 2012

Status

approved