A327015 Number of equivalence classes of pairs of permutations in S_n where two pairs are equivalent if they are simultaneously conjugate to each other or simultaneously conjugate to each other after a reversal of one pair.

1, 1, 3, 8, 28, 98, 518, 3096, 23415, 201795, 1973189, 21347935, 253282652, 3263902430

Offset: 0

Author

Derek Lim, Aug 13 2019

Keywords

• nonn
• more

Examples

			For n = 2, representatives of the a(2) = 3 classes are: (e,e), (e, (12)), ((12),(12)), where e is identity.
		

Links

• Amit Harlev, Charles R. Johnson, and Derek Lim, The Doubly Stochastic Single Eigenvalue Problem: A Computational Approach, arXiv:1908.03647 [math.SP], 2019.

Crossrefs

Cf. A110143, A327014.

Formula

a(n) = (A110143(n) + A327014(n)) / 2.