

A047832


Number of selfcomplementary binary relations on a 2nelement set.


7



2, 36, 5600, 11220000, 293293716992, 102484848265030656, 491247277315343649710080, 32966971058719932671168222859264, 31464896751148469761776612436741418123264, 432450241375084625203842385525712986695638650716160
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OFFSET

1,1


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..40
D. Wille, Enumeration of selfcomplementary structures, J. Comb. Theory B 25 (1978) 143150.


FORMULA

a(n) = A000171(4*n+1).


MATHEMATICA

Needs["Combinatorica`"]; Table[ Print[an = GraphPolynomial[4*n + 1, x] /. x > 1]; an, {n, 1, 9}] (* JeanFrançois Alcover, Aug 12 2013 *)


CROSSREFS

Cf. A000171.
Sequence in context: A319507 A001070 A095229 * A004003 A060739 A333209
Adjacent sequences: A047829 A047830 A047831 * A047833 A047834 A047835


KEYWORD

nonn,nice


AUTHOR

Vladeta Jovovic


EXTENSIONS

Terms a(10) and beyond from Andrew Howroyd, Sep 17 2018


STATUS

approved



