A293917 - OEIS

A293917

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

1, 19, 252, 3441, 52938, 919077, 17783732, 379205917, 8832657552, 223147872970, 6078406509776, 177602480890788, 5541376133638552, 183896037042429100, 6468180930063929404, 240368899912444102612, 9410883311417206598912, 387192534875365889313239

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OFFSET

4,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..404

FORMULA

a(n) ~ (exp(-3) - exp(-4)) * 2^(n + 1/2) * n^n / exp(n). - Vaclav Kotesovec, Oct 25 2017

CROSSREFS

Column k=4 of A293881.

Sequence in context: A018912 A021202 A125454 * A009762 A017952 A055433

Adjacent sequences: A293914 A293915 A293916 * A293918 A293919 A293920

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 19 2017

STATUS

approved