A012081 arcsinh(arcsin(tan(x)))=x+2/3!*x^3+24/5!*x^5+888/7!*x^7+68352/9!*x^9...
1, 2, 24, 888, 68352, 8853888, 1724221056, 470304668928, 171029448056832, 79950698284462080, 46709069479002931200, 33347332565041919950848, 28565775294718770340331520, 28915860353300526164581613568
Offset: 0