A013242 arctanh(log(x+1)-tan(x))=-1/2!*x^2-6/4!*x^4+8/5!*x^5-150/6!*x^6...

-1, 0, -6, 8, -150, 448, -7560, 38432, -650160, 4827328, -85887648, 855019904, -16230758544, 204362847232, -4163699379840, 63548399361536, -1392682970270592, 24960951809133568, -588583828329908480