The On-Line Encyclopedia of Integer Sequences (OEIS)

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A293915

Number of linear chord diagrams having n chords and minimal chord length two.
(history; published version)

#7 by Vaclav Kotesovec at Wed Oct 25 18:08:36 EDT 2017

STATUS

editing

approved

#6 by Vaclav Kotesovec at Wed Oct 25 17:18:31 EDT 2017

FORMULA

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

#5 by Vaclav Kotesovec at Wed Oct 25 16:14:17 EDT 2017

FORMULA

Recurrence: (24*n^2 - 182*n + 339)*a(n) = (96*n^3 - 800*n^2 + 1894*n - 991)*a(n-1) - (96*n^4 - 824*n^3 + 1804*n^2 + 650*n - 3571)*a(n-2) + 2*(144*n^4 - 1788*n^3 + 8032*n^2 - 15489*n + 10821)*a(n-3) - 2*(144*n^4 - 2028*n^3 + 10452*n^2 - 23337*n + 18994)*a(n-4) + (96*n^4 - 1592*n^3 + 9452*n^2 - 23794*n + 21419)*a(n-5) + (96*n^3 - 1040*n^2 + 3550*n - 3841)*a(n-6) + (24*n^2 - 134*n + 181)*a(n-7). - Vaclav Kotesovec, Oct 25 2017

STATUS

approved

editing

#4 by Alois P. Heinz at Fri Oct 20 17:12:50 EDT 2017

STATUS

editing

approved

#3 by Alois P. Heinz at Thu Oct 19 16:26:54 EDT 2017

LINKS

Alois P. Heinz, <a href="/A293915/b293915.txt">Table of n, a(n) for n = 2..404</a>

#2 by Alois P. Heinz at Thu Oct 19 15:57:22 EDT 2017

NAME

allocated for Alois P. Heinz

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

DATA

1, 4, 26, 230, 2509, 32422, 484180, 8203519, 155460169, 3257843351, 74802301553, 1867393802229, 50358879172771, 1458899632505052, 45185432509804438, 1489952528266230695, 52112346134820625126, 1926974225717684659004, 75110765705496454871866

OFFSET

2,2

CROSSREFS

Column k=2 of A293881.

KEYWORD

allocated

nonn

AUTHOR

Alois P. Heinz, Oct 19 2017

STATUS

approved

editing

#1 by Alois P. Heinz at Thu Oct 19 15:52:57 EDT 2017

NAME

allocated for Alois P. Heinz

KEYWORD

allocated

STATUS

approved