login
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, 1, 3, 8, 28, 98, 518, 3096, 23415, 201795, 1973189, 21347935, 253282652, 3263902430
OFFSET
0,3
LINKS
Amit Harlev, Charles R. Johnson, and Derek Lim, The Doubly Stochastic Single Eigenvalue Problem: A Computational Approach, arXiv:1908.03647 [math.SP], 2019.
FORMULA
a(n) = (A110143(n) + A327014(n)) / 2.
EXAMPLE
For n = 2, representatives of the a(2) = 3 classes are: (e,e), (e, (12)), ((12),(12)), where e is identity.
CROSSREFS
Sequence in context: A026627 A376230 A148866 * A151431 A245892 A263103
KEYWORD
nonn,more
AUTHOR
Derek Lim, Aug 13 2019
STATUS
approved