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A039765 Number of edges in the Hasse diagrams for the D-analogs of the partition lattices. 3
0, 0, 4, 31, 240, 1931, 16396, 147589, 1408224, 14214559, 151394940, 1696783221, 19958826080, 245788962199, 3161635135340, 42390110260685, 591257152058944, 8563898444592927, 128598641049231996 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..18.

R. Suter, Two analogues of a classical sequence, J. Integer Sequences, Vol. 3 (2000), #P00.1.8.

FORMULA

E.g.f.: f_4(x)*g_1(x)*e_1(f_2(x)) + e_1(x)*g_4(x)*e_1(g_2(x)) where e_n(x) = 1/n exp(n x); f_n(x) = 1/n (exp(n x) - 1); g_n(x) = 1/n (exp(n x) - 1 - n x).

MATHEMATICA

max = 18; e[n_, x_] := E^(n*x)/n; f[n_, x_] := (E^(n*x) - 1)/n; g[n_, x_] := (E^(n*x) - 1 - n*x)/n; se = Series[ f[4, x]*g[1, x]*e[1, f[2, x]] + e[1, x]*g[4, x]*e[1, g[2, x]], {x, 0, max}]; CoefficientList[se, x]*Range[0, max]! (* Jean-Fran├žois Alcover, May 04 2012, after e.g.f. *)

CROSSREFS

Edges in the Hasse diagrams for partition lattices: A003128, B-analogs = A039759.

Sequence in context: A014537 A136284 A183911 * A001091 A309184 A077615

Adjacent sequences:  A039762 A039763 A039764 * A039766 A039767 A039768

KEYWORD

nonn,nice

AUTHOR

Ruedi Suter (suter(AT)math.ethz.ch)

STATUS

approved

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Last modified November 13 08:18 EST 2019. Contains 329093 sequences. (Running on oeis4.)