20891972domain: NAppears in sequencesApproximation of the 2-adic integer arctan(4) up to 2^n.at n=25A309756Approximation of the 2-adic integer arctan(4) up to 2^n.at n=26A309756Approximation of the 2-adic integer arctan(4) up to 2^n.at n=27A309756Approximation of the 2-adic integer arctan(4) up to 2^n.at n=28A309756