-7375domain: ZAppears in sequencestan(sin(x)-tanh(x))=1/3!*x^3-15/5!*x^5+271/7!*x^7-7375/9!*x^9...at n=3A013381a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) - a(n-4), n>=4; a(0) = 1, a(1) = 1, a(2) = 2, a(3) = 3.at n=21A193885