176823domain: NAppears in sequencesNumber of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 2 adjacent element pairs in decreasing order.at n=8A151583E.g.f. A(x) satisfies: 1 = Sum_{n>=0} (exp(n*x) - A(x))^n / n!.at n=6A326095