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A217246 Number of highly irregular connected graphs with n nodes. 0
1, 1, 0, 1, 0, 1, 0, 3, 3, 13, 21, 110, 474, 2545, 18696, 136749, 1447003, 18772435, 303050079, 6239596472 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

COMMENTS

A connected graph is highly irregular if the neighbors of each vertex have distinct degrees. Such graphs exist on all orders except 3, 5 and 7. [from the McKay link]

LINKS

Table of n, a(n) for n=1..20.

Avraham Itzhakov and Michael Codish, Breaking Symmetries in Graph Search with Canonizing Sets, arXiv:1511.08205 [cs.AI], 2015

Brendan McKay, Combinatorial Data (on graphs); see bottom of page

EXAMPLE

a(4) = 1, the only such graph is the linear graph: o--o--o--o

CROSSREFS

Sequence in context: A209390 A095336 A072552 * A186743 A219314 A288146

Adjacent sequences:  A217243 A217244 A217245 * A217247 A217248 A217249

KEYWORD

more,nonn

AUTHOR

Joerg Arndt, Mar 16 2013

EXTENSIONS

a(16)-a(19) from Michael Codish, Dec 01 2015

a(20) from Michael Codish, Jan 17 2016

STATUS

approved

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Last modified October 21 14:42 EDT 2021. Contains 348155 sequences. (Running on oeis4.)