A324163 - OEIS

A324163

Triangle read by rows: T(n,k) is the number of connected k-regular simple graphs on n labeled vertices, (0 <= k < n).

1, 0, 1, 0, 0, 1, 0, 0, 3, 1, 0, 0, 12, 0, 1, 0, 0, 60, 70, 15, 1, 0, 0, 360, 0, 465, 0, 1, 0, 0, 2520, 19320, 19355, 3507, 105, 1, 0, 0, 20160, 0, 1024380, 0, 30016, 0, 1, 0, 0, 181440, 11166120, 66462480, 66462606, 11180820, 286884, 945, 1

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,9

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..210

FORMULA

Column k is the logarithmic transform of column k of A059441.

EXAMPLE

Triangle begins:

0, 1;

0, 0, 1;

0, 0, 3, 1;

0, 0, 12, 0, 1;

0, 0, 60, 70, 15, 1;

0, 0, 360, 0, 465, 0, 1;

0, 0, 2520, 19320, 19355, 3507, 105, 1;

0, 0, 20160, 0, 1024380, 0, 30016, 0, 1;

...

CROSSREFS

Column k=2 is A001710(n-1) for n >= 3.

Column k=3 is aerated A004109.

Column k=4 is A272905.

Row sums are A322659.

Cf. A059441 (not necessarily connected), A068934 (unlabeled).

Sequence in context: A034370 A144402 A264429 * A127537 A265314 A364207

Adjacent sequences: A324160 A324161 A324162 * A324164 A324165 A324166

KEYWORD

nonn,tabl

AUTHOR

Andrew Howroyd, Sep 02 2019

STATUS

approved