A218096 Number of transitive reflexive early confluent binary relations R on n labeled elements with max_{x}(|{y : xRy}|) = 6.

4683, 137774, 3794378, 105494886, 3068829477, 94494907584, 3085918099231, 106818340013957, 3913397076494906, 151442406160585540, 6177363078563029080, 265028384609314768260, 11934799080680963824449, 563007076962063332175612, 27770258520873025001499693

Offset

6,1

Comments

R is early confluent iff (xRy and xRz) implies (yRz or zRy) for all x, y, z.

References

A. P. Heinz (1990). Analyse der Grenzen und Möglichkeiten schneller Tableauoptimierung. PhD Thesis, Albert-Ludwigs-Universität Freiburg, Freiburg i. Br., Germany.

Links

Alois P. Heinz, Table of n, a(n) for n = 6..200

Formula

E.g.f.: t_6(x)-t_5(x), with t_k(x) = exp (Sum_{m=1..k} x^m/m! * t_{k-m}(x)) if k>=0 and t_k(x) = 0 else.

a(n) = A210914(n) - A210913(n).

Maple

t:= proc(k) option remember; `if`(k<0, 0,
      unapply(exp(add(x^m/m! *t(k-m)(x), m=1..k)), x))
    end:
egf:= t(6)(x)-t(5)(x):
a:= n-> n!* coeff(series(egf, x, n+1), x, n):
seq(a(n), n=6..20);

Mathematica

m = 6; t[k_] := t[k] = If[k<0, 0, Function[x, Exp[Sum[x^m/m!*t[k-m][x], {m, 1, k}]]]] ; egf = t[m][x]-t[m-1][x]; a[n_] := n!*Coefficient[Series[egf, {x, 0, n+1}], x, n]; Table[a[n], {n, m, 20}] (* Jean-François Alcover, Feb 14 2014, after Maple *)

Crossrefs

Column k=6 of A135313.

Sequence in context: A190131 A226801 A320620 * A293583 A263066 A252773

Adjacent sequences: A218093 A218094 A218095 * A218097 A218098 A218099

Keyword

nonn

Author

Alois P. Heinz, Oct 20 2012

Status

approved