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A018195 Possible numbers of complements of topologies on 4 points. 0
1, 3, 4, 7, 12, 14, 15, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..7.

J. I. Brown and S. Watson, The number of complements of a topology on n points is at least 2^n (except for some special cases), Discr. Math., 154 (1996), 27-39.

CROSSREFS

Sequence in context: A244819 A305185 A083561 * A086417 A051215 A192112

Adjacent sequences:  A018192 A018193 A018194 * A018196 A018197 A018198

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified June 20 21:35 EDT 2021. Contains 345255 sequences. (Running on oeis4.)