D[Coth[z], {z, n}] == Coth[z] KroneckerDelta[n] - Csch[z]^2 KroneckerDelta[n - 1] - (-I)^n n Sum[(((-1)^(j + k) Binomial[n - 1, k])/(k + 1)) Sinh[z]^(-2 k - 2) 2^(n - 2 k) Binomial[2 k, j] (k - j)^(n - 1) Sinh[(I n Pi)/2 + 2 (k - j) z], {k, 0, n - 1}, {j, 0, k - 1}] /; Element[n, Integers] && n >= 0

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2001-10-29