A345248 Number of labeled connected simple graphs on n vertices without cycles of length 4.

1, 1, 4, 28, 302, 4776, 106732, 3249352, 131290812, 6922560160, 470586936176, 40833342324864, 4482709905772936, 617622136930640128, 106013904370382120400, 22516967955697072408576, 5880701545642715236590608, 1877504184190590494772860928

Offset

1,3

Comments

From R. J. Mathar, Apr 03 2022 (Start)

The sequence contains the row sums of the number of labeled connected simple graphs on V vertices with E edges, the triangle with V>=0, E>=0:

1 ;

1 ;

0 1;

0 0 3 1;

0 0 0 16 12;

0 0 0 0 125 162 15;

0 0 0 0 0 1296 2580 900;

0 0 0 0 0 0 16807 47715 35595 6615 ;

0 0 0 0 0 0 0 262144 1006488 1270080 619920 90720;

0 0 0 0 0 0 0 0 4782969 23859108 44893170 39867660 15892065 1995840 ;

(End)

Links

Table of n, a(n) for n=1..18.

Crossrefs

LOG transform of A345249.

A077269 counts isomorphism classes.

Cf. A345218.

Sequence in context: A362475 A274043 A007152 * A295258 A177554 A316212

Adjacent sequences: A345245 A345246 A345247 * A345249 A345250 A345251

Keyword

nonn,hard

Author

Brendan McKay, Jun 12 2021

Status

approved