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 A344662 a(n) is the number of preference profiles in the stable marriage problem with n men and n women so that they form n pairs of people of different genders who rank each other first, and so that the men's preferences arranged in a matrix form a Latin square. 2
 1, 2, 96, 746496, 1284211998720, 2427160677580800000000, 6166762687851449045483520000000000, 45287412266290145430585597857888710164480000000000, 1555956528335898586085189699733983238252540690603399394099200000000000, 395245501240598487865502317687285665641954608158944047815164739503046322343116800000000000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Two people who rank each other first are called soulmates. The profiles in this sequence are required to have n pairs of soulmates. The profiles with n pairs of soulmates are counted by sequence A343698. The profiles such that the men's preference form a Latin square are counted by A343696. The profiles in this sequence are the intersection of profiles in A343696 and A343698. The Gale-Shapley algorithm (both men-proposing and women-proposing) on the preference profiles described by this sequence ends in one round. LINKS Table of n, a(n) for n=1..10. Matvey Borodin, Eric Chen, Aidan Duncan, Tanya Khovanova, Boyan Litchev, Jiahe Liu, Veronika Moroz, Matthew Qian, Rohith Raghavan, Garima Rastogi, and Michael Voigt, Sequences of the Stable Matching Problem, arXiv:2201.00645 [math.HO], 2021. Wikipedia, Gale-Shapley algorithm. FORMULA a(n) = (n-1)!^n * A002860(n) = A343696(n)/n^n. EXAMPLE For n = 3, there are A002860(3) = 12 ways to set up the men's preference profiles, where A002860(n) is the number of Latin squares of order n. The men's first preferences set the women's first preferences, so we only need to complete the women's profiles with other preferences, which can be done in 2!^3 = 8 ways. Thus, A344662(3) = 12 * 8 = 96. CROSSREFS Cf. A002860, A185141, A343694, A343695, A343696, A343697, A343698, A344663. Sequence in context: A337653 A168442 A091810 * A165642 A057528 A346565 Adjacent sequences: A344659 A344660 A344661 * A344663 A344664 A344665 KEYWORD nonn AUTHOR Tanya Khovanova and MIT PRIMES STEP Senior group, May 30 2021 STATUS approved

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Last modified May 18 08:45 EDT 2024. Contains 372618 sequences. (Running on oeis4.)