A362650 - OEIS

A362650

Number of nonisomorphic unordered triples of involutions on an n-set.

1, 1, 4, 7, 29, 63, 258, 759, 3263, 12250, 56330, 250841, 1235205, 6113154, 31941407, 169613842, 932670975, 5223815423, 30040926830, 175918987173, 1053086891249, 6413469553076, 39818396779256, 251251607202822, 1613056058498375, 10514730684539068

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OFFSET

0,3

COMMENTS

Isomorphism is up to permutation of the elements of the n-set.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..50

EXAMPLE

The a(3) = 7 nonisomorphic triples of involutions are:

{(), (), ()},

{(), (), (23)},

{(), (23), (23)},

{(), (23), (12)},

{(23), (23), (23)},

{(23), (23), (12)},

{(23), (12), (13)}.

CROSSREFS

Column k=3 of A362648.

Cf. A362646, A362649.

Sequence in context: A176966 A117977 A272870 * A176750 A030687 A149081

Adjacent sequences: A362647 A362648 A362649 * A362651 A362652 A362653

KEYWORD

nonn

AUTHOR

Andrew Howroyd, May 01 2023

STATUS

approved