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 A362764 Number of nonisomorphic 2-sets of permutations of an n-set. 3

%I #6 May 03 2023 21:36:36

%S 0,1,5,23,89,484,2904,22002,190555,1876337,20445337,244087420,

%T 3161870208,44155439706,661065427533,10561205778825,179324080364960,

%U 3224650449785185,61218223893368714,1223523447160283853,25679025453032962132,564657001202726477313

%N Number of nonisomorphic 2-sets of permutations of an n-set.

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

%H Andrew Howroyd, <a href="/A362764/b362764.txt">Table of n, a(n) for n = 1..50</a>

%F a(n) = A362645(n) - A000041(n).

%e The a(3)=5 sets with permutations shown in cycle notation are:

%e {(1)(2)(3), (1)(23)},

%e {(1)(2)(3), (123)},

%e {(1)(23), (12)(3)},

%e {(1)(23), (123)},

%e {(123), (132)}.

%Y Column k=2 of A362763.

%Y Cf. A000041, A362645, A362765.

%K nonn

%O 1,3

%A _Andrew Howroyd_, May 03 2023

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Last modified September 17 04:45 EDT 2024. Contains 375985 sequences. (Running on oeis4.)