login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A284716 Number of indecomposable permutations avoiding the pattern 2143. 1
1, 1, 3, 13, 63, 330, 1838, 10758, 65586, 413639, 2684469, 17852715, 121256457, 838843641, 5897455515, 42058344077, 303787163823, 2219452035639, 16383022072549, 122066094872139, 917245868993865, 6946236553301334, 52979616083094066, 406741647662973594 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

A. L. L. Gao, S. Kitaev, P. B. Zhang. On pattern avoiding indecomposable permutations, arXiv:1605.05490 [math.CO], 2016.

FORMULA

a(n) ~ 4 * 3^(2*n+1/2) / (Pi*n^4). - Vaclav Kotesovec, Apr 02 2017

MATHEMATICA

Rest[CoefficientList[Series[2*x - 1 + (1-x)^2 * (1 + 5*x - (1-9*x)^(3/4) * (1-x)^(1/4) * HypergeometricPFQ[{-1/4, 3/4}, {1}, 64*x/((x-1)*(1-9*x)^3)])/(6*x^2), {x, 0, 30}], x]] (* Vaclav Kotesovec, Apr 02 2017 *)

CROSSREFS

Sequence in context: A007855 A193112 A192729 * A107097 A202837 A180111

Adjacent sequences:  A284713 A284714 A284715 * A284717 A284718 A284719

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 02 2017

EXTENSIONS

More terms from Vaclav Kotesovec, Apr 02 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 24 12:01 EDT 2019. Contains 322429 sequences. (Running on oeis4.)