cp's OEIS Frontend

A362645 Number of nonisomorphic unordered pairs of permutations of an n-set.

%I A362645 #9 May 02 2023 17:49:19
%S A362645 1,1,3,8,28,96,495,2919,22024,190585,1876379,20445393,244087497,
%T A362645 3161870309,44155439841,661065427709,10561205779056,179324080365257,
%U A362645 3224650449785570,61218223893369204,1223523447160284480,25679025453032962924,564657001202726478315
%N A362645 Number of nonisomorphic unordered pairs of permutations of an n-set.
%C A362645 Isomorphism is up to permutation of the elements of the n-set.
%H A362645 Andrew Howroyd, <a href="/A362645/b362645.txt">Table of n, a(n) for n = 0..50</a>
%e A362645 The a(3)=8 pairs of permutations with permutations shown in cycle notation are:
%e A362645   {(1)(2)(3), (1)(2)(3)},
%e A362645   {(1)(2)(3), (1)(23)},
%e A362645   {(1)(2)(3), (123)},
%e A362645   {(1)(23), (1)(23)},
%e A362645   {(1)(23), (12)(3)},
%e A362645   {(1)(23), (123)},
%e A362645   {(123), (123)},
%e A362645   {(123), (132)}.
%Y A362645 Column k=2 of A362644.
%Y A362645 Cf. A362649.
%K A362645 nonn
%O A362645 0,3
%A A362645 _Andrew Howroyd_, May 01 2023