Expansion of sin(sin(tanh(x))).A009473Expansion of sin(sin(tanh(x))).Terms a(0) =1a(1) =-4a(2) =68a(3) =-2472a(4) =152144a(5) =-14034560a(6) =1799730624a(7) =-304857999232External referencesoeis: A009473