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A185119
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Number of connected 2-regular simple graphs on n vertices with girth at least 9.
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11
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1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
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OFFSET
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0
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LINKS
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FORMULA
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a(0)=1; for 0<n<9 a(n)=0; for n>=9 , a(n)=1.
Inverse Euler transformation of A185329.
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EXAMPLE
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The null graph is vacuously 2-regular and, being acyclic, has infinite girth.
There are no 2-regular simple graphs with 1 or 2 vertices.
The n-cycle has girth n.
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CROSSREFS
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2-regular simple graphs with girth at least 9: this sequence (connected), A185229 (disconnected), A185329 (not necessarily connected).
Connected k-regular simple graphs with girth at least 9: A186729 (all k), A186719 (triangular array), this sequence (k=2).
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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