A293996 Number of linear chord diagrams having n chords and no chord length larger than four.
1, 1, 3, 15, 105, 315, 1141, 4779, 21101, 80559, 314185, 1267551, 5160933, 20504123, 81554685, 326682775, 1310978305, 5239019143, 20931551661, 83743554723, 335175239813, 1340542340399, 5360923216953, 21444223178271, 85786427569333, 343141430067947
Offset: 0
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (2,2,11,60,-18,-26,-108,-48)
Crossrefs
Column k=4 of A293960.
Formula
G.f.: -(2*x^4+4*x^3+x^2+x-1) / ((4*x-1) * (12*x^7+30*x^6+14*x^5+8*x^4-13*x^3 -6*x^2 -2*x-1)).