A369921 Number of cover relations summed over the rank-1 labeled posets on [n].
0, 0, 2, 18, 204, 2940, 56670, 1471806, 52067512, 2520298584, 167850357210, 15435027907530, 1967345286257604, 348527628228821652, 86057693880611800438, 29677160119074814383030, 14321851348104417100842480
Offset: 0
Keywords
Links
- Eric Weisstein's World of Mathematics, Cover Relation.
Programs
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Mathematica
nn = 16; Table[Table[n!, {n, 0, nn}] CoefficientList[D[Series[Sum[Exp[y x]^Binomial[n, i]*Exp[ x]^(2^n - Binomial[n, i] - 1) x^n/n!, {n, 0, nn}], {x, 0, nn}], y] /. y -> 1, x]*i, {i, 1, nn - 1}] // Total
Formula
a(n) = Sum_{k=1..floor(n^2/4)} A052296(n,k)*k.
Comments