A293920 - OEIS

A293920

Number of linear chord diagrams having n chords and minimal chord length seven.

1, 159, 7564, 245964, 6996588, 193799140, 5489211751, 162272284974, 5047554996855, 165595774518042, 5728636935767404, 208700950019470460, 7993330299623656154, 321268248361695869991, 13525506763517368392668, 595415097485805608016210, 27361311228606445955339071

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OFFSET

7,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..405

FORMULA

a(n) ~ (exp(-6) - exp(-7)) * 2^(n + 1/2) * n^n / exp(n). - Vaclav Kotesovec, Oct 25 2017

CROSSREFS

Column k=7 of A293881.

Sequence in context: A232408 A121800 A121804 * A281336 A205164 A221011

Adjacent sequences: A293917 A293918 A293919 * A293921 A293922 A293923

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 19 2017

STATUS

approved