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
The hailstone number of each number in the form 2^n-1 when n>1 is, as stated on the OEIS by Alexandre Herrera, "a(2n) = 1 + a(2n-1) for n >= 2" where a(n) is the hailstone number of 2^n-1 OEIS A193688. Simply Put the hailstone numbers of integers one less than a power of 2 come in groups of 2 or ...