Number of permutations (p_1, ..., p_n) of {1,...,n} that are "balanced" in the sense that the sum of k*p_k equals the sum of (n+1-k)*p_k; equivalently, the expected value of k*p_k is (expected value of k) times (expected value of p_k), assuming the uniform distribution.

A056876

Number of permutations (p_1, ..., p_n) of {1,...,n} that are "balanced" in the sense that the sum of k*p_k equals the sum of (n+1-k)*p_k; equivalently, the expected value of k*p_k is (expected value of k) times (expected value of p_k), assuming the uniform distribution.

Terms

    a(0) =1a(1) =1a(2) =0a(3) =0a(4) =2a(5) =6a(6) =0a(7) =184a(8) =936a(9) =6688a(10) =0a(11) =420480a(12) =4298664a(13) =44405142a(14) =0a(15) =6732621476a(16) =92014579912a(18) =0a(22) =0

External references