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A303792 Number of connected matchstick graphs on n nodes. 1
1, 1, 2, 5, 13, 50 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(7) >= 209.

LINKS

Table of n, a(n) for n=1..6.

Eric Weisstein's World of Mathematics, Connected Graph

Eric Weisstein's World of Mathematics, Matchstick Graph

FORMULA

a(6) = A059103(6) - 1.

a(n) <= A059103(n).

EXAMPLE

a(6) is one less than A059103(6) because the 3-prism graph Y_3 cannot be drawn in an embedding that is both planar and unit-distance.

There appear to be 13 connected graphs on 7 nodes that are unit-distance but non-matchstick (including Y_3+e and the Moser spindle).

CROSSREFS

Cf. A059103.

Sequence in context: A269068 A098716 A082938 * A059103 A260709 A112836

Adjacent sequences:  A303789 A303790 A303791 * A303793 A303794 A303795

KEYWORD

nonn,hard,more

AUTHOR

Eric W. Weisstein, Apr 30 2018

STATUS

approved

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Last modified June 24 09:55 EDT 2019. Contains 324323 sequences. (Running on oeis4.)