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A325455 Triangle read by rows: T(n,k) is the number of connected graphs on n unlabeled nodes with circumference k, (n >= 3, k >= 3). 4
1, 1, 3, 4, 6, 8, 10, 24, 24, 48, 30, 87, 116, 226, 383, 83, 342, 527, 1283, 2663, 6196, 257, 1324, 2644, 6644, 17613, 55468, 177083 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

3,3

COMMENTS

Trees are excluded since they do not have any cycle.

LINKS

Table of n, a(n) for n=3..30.

Eric Weisstein's World of Mathematics, Graph Circumference

Eric Weisstein's World of Mathematics, Hamiltonian Graph

EXAMPLE

Triangle begins:

    1;

    1,    3;

    4,    6,    8;

   10,   24,   24,   48;

   30,   87,  116,  226,   383;

   83,  342,  527, 1283,  2663,  6196;

  257, 1324, 2644, 6644, 17613, 55468, 177083;

  ...

CROSSREFS

Right diagonal is A003216.

Row sums are A241841.

Cf. A128042, A309524, A325447.

Sequence in context: A343883 A277319 A176986 * A069357 A337455 A080728

Adjacent sequences:  A325452 A325453 A325454 * A325456 A325457 A325458

KEYWORD

nonn,tabl,more

AUTHOR

Andrew Howroyd, Sep 06 2019

STATUS

approved

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Last modified May 13 05:02 EDT 2021. Contains 343836 sequences. (Running on oeis4.)