A088976 Breadth-first traversal of the Collatz tree, with the even child of each node traversed prior to its odd child. If the Collatz 3n+1 conjecture is true, this is a permutation of all positive integers.

1, 2, 4, 8, 16, 32, 5, 64, 10, 128, 21, 20, 3, 256, 42, 40, 6, 512, 85, 84, 80, 13, 12, 1024, 170, 168, 160, 26, 24, 2048, 341, 340, 336, 320, 53, 52, 48, 4096, 682, 680, 113, 672, 640, 106, 104, 17, 96, 8192, 1365, 1364, 227, 1360, 226, 1344, 1280, 213, 212, 35, 208

Offset: 0

Author

David Eppstein, Oct 31 2003

Keywords

• easy
• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 0..3517

Crossrefs

Cf. A127824 (terms at the same depth are sorted).

Programs

Python

def A088976():
    yield 1
    for x in A088976():
        yield 2*x
        if x > 4 and x % 6 == 4:
            yield (x - 1)//3
a = A088976(); print([next(a) for _ in range(100)])