55023domain: NAppears in sequencesIn the "3x+1" problem, let 1 denote a halving step and 0 denote an x->3x+1 step. Then a(n) is obtained by writing the sequence of steps needed to reach 1 from 2n and reading it as a decimal number.at n=21A125711Number of 4-row-restricted Baxter slicings of size n.at n=9A342290