Least k starting a chain of (2n+1) consecutive integers {h(k+i)}, i=0,1,...,2n, where h(k) is the length of the finite set {k, f(k), f(f(k)), ..., 1} in the Collatz (or 3x + 1) problem, with the property that h(k) = h(k+2n), h(k+1) = h(k+2n-1), ..., h(k+n-1) = h(k+n+1).

A268486

Least k starting a chain of (2n+1) consecutive integers {h(k+i)}, i=0,1,...,2n, where h(k) is the length of the finite set {k, f(k), f(f(k)), ..., 1} in the Collatz (or 3x + 1) problem, with the property that h(k) = h(k+2n), h(k+1) = h(k+2n-1), ..., h(k+n-1) = h(k+n+1).