OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1668
Christopher Bao, Yunseo Choi, Katelyn Gan, and Owen Zhang, On a Conjecture by Baril, Cerbai, Khalil, and Vajnovszki on Two Restricted Stacks, arXiv:2308.09344 [math.CO], 2023.
Giulio Cerbai, Anders Claesson, and Luca Ferrari, Stack sorting with restricted stacks, arXiv:1907.08142 [cs.DS], 2019.
Giulio Cerbai, Anders Claesson, Luca Ferrari, and Einar Steingrímsson, Sorting with pattern-avoiding stacks: the 132-machine, arXiv:2006.05692 [math.CO], 2020.
Lapo Cioni and Luca Ferrari, Enumerative Results on the Schröder Pattern Poset, In: Dennunzio A., Formenti E., Manzoni L., Porreca A. (eds) Cellular Automata and Discrete Complex Systems, AUTOMATA 2017, Lecture Notes in Computer Science, vol 10248. See p. 65.
FORMULA
a(n) = A014140(n) - n.
MAPLE
a:= proc(n) option remember; `if`(n<3, 1+n^2,
(6*n*a(n-1)-(9*n-3)*a(n-2)+(4*n-2)*a(n-3))/(n+1))
end:
seq(a(n), n=0..30); # Alois P. Heinz, Oct 01 2019
MATHEMATICA
MapIndexed[#1 - First[#2] + 1 &, CoefficientList[Series[1/(1 - x)^2*(1 - Sqrt[1 - 4 x])/(2 x), {x, 0, 27}], x]] (* Michael De Vlieger, Oct 01 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric M. Schmidt, Nov 08 2017
STATUS
approved