A398113 Number of rooted unlabeled 4-gonal cacti having n polygons with each vertex in at most two polygons.

1, 1, 3, 8, 28, 98, 372, 1438, 5745, 23336, 96458, 403655, 1708235, 7295057, 31403624, 136114956, 593550279, 2602087433, 11461700812, 50701757419, 225144913614, 1003250612079, 4484660492556, 20105017963779, 90371345506681, 407208919403669, 1839006927985202

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..500

Index entries for sequences related to cacti

Prog

(PARI) Vec(R(25, 4)) \\ Needs R(n, k) from A398112

Crossrefs

Column k=4 of A398112.

Sequence in context: A362645 A026627 A376230 * A148866 A327015 A151431

Adjacent sequences: A398110 A398111 A398112 * A398114 A398115 A398119

Keyword

nonn,new

Author

Andrew Howroyd, Jul 23 2026

Status

approved