A293995 Number of linear chord diagrams having n chords and no chord length larger than three.
1, 1, 3, 15, 35, 103, 343, 979, 2915, 8935, 26559, 79499, 239547, 717455, 2151095, 6459027, 19371507, 58106071, 174349295, 523022555, 1569013931, 4707208351, 14121515303, 42364215075, 127093528675, 381280144743, 1143838446943, 3431519977579, 10294558387995
Offset: 0
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (2,1,8,-6)
Crossrefs
Column k=3 of A293960.
Programs
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Mathematica
LinearRecurrence[{2,1,8,-6},{1,1,3,15},30] (* Harvey P. Dale, Aug 08 2021 *)
Formula
G.f.: -(x-1)/((3*x-1)*(2*x^3-2*x^2-x-1)).