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A369223 Number of uniquely colorable simple graphs on n nodes. 1
1, 1, 2, 3, 6, 11, 35, 134, 1183, 21319, 761871 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
The only disconnected uniquely colorable graphs are the empty graphs on n > 1 nodes.
LINKS
Eric Weisstein's World of Mathematics, Simple Graph.
Eric Weisstein's World of Mathematics, Uniquely Colorable Graph.
FORMULA
a(n) = Sum_{k=1..n} A369227(n,k).
EXAMPLE
n = 1: singleton graph K_1 (1 graph).
n = 2: 2-empty graph, path graph P_2 (2 graphs).
n = 3: 3-empty graph, path graph P_3, triangle graph C_3 = K_3 (3 graphs).
n = 4: 4-empty graph, claw graph K_{1,3}, diamond graph K_{1,1,2} = K_4-e, P_4, square graph C_4, tetrahedral graph K_4 (6 graphs).
CROSSREFS
Cf. A001349.
Cf. A369227 (triangle by chromatic number).
Sequence in context: A086209 A022490 A102952 * A065653 A275783 A102021
KEYWORD
nonn,more
AUTHOR
Eric W. Weisstein, Jan 16 2024
STATUS
approved

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Last modified June 15 05:55 EDT 2024. Contains 373402 sequences. (Running on oeis4.)