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 A362764 Number of nonisomorphic 2-sets of permutations of an n-set. 3
 0, 1, 5, 23, 89, 484, 2904, 22002, 190555, 1876337, 20445337, 244087420, 3161870208, 44155439706, 661065427533, 10561205778825, 179324080364960, 3224650449785185, 61218223893368714, 1223523447160283853, 25679025453032962132, 564657001202726477313 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Isomorphism is up to permutation of the elements of the n-set. LINKS Andrew Howroyd, Table of n, a(n) for n = 1..50 FORMULA a(n) = A362645(n) - A000041(n). EXAMPLE The a(3)=5 sets with permutations shown in cycle notation are: {(1)(2)(3), (1)(23)}, {(1)(2)(3), (123)}, {(1)(23), (12)(3)}, {(1)(23), (123)}, {(123), (132)}. CROSSREFS Column k=2 of A362763. Cf. A000041, A362645, A362765. Sequence in context: A255803 A121329 A246175 * A283224 A178834 A331720 Adjacent sequences: A362761 A362762 A362763 * A362765 A362766 A362767 KEYWORD nonn AUTHOR Andrew Howroyd, May 03 2023 STATUS approved

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Last modified August 10 09:30 EDT 2024. Contains 375044 sequences. (Running on oeis4.)