recaman 0.1.0

Iterator for the Recaman's sequence
Documentation 
# Recaman

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0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9, 24, 8, 25, 43, 62, 42, 63, 41, 18, 42, 17, 43, 16, 44, 15, 45, 14, 46, 79, 113, 78, 114, 77, 39, 78, 38, 79, 37, 80, 36, 81, 35, 82, 34, 83, 33, 84, 32, 85, 31, 86, 30, 87, 29, 88, 28, 89, 27, 90, 26, 91, 157, 224, 156, 225, 155

[A005132][oeis] Recamán's sequence.

- `A(0) = 0`
- For `n > 0`
    - `A(n) = A(n-1) - n` if positive and not already in the sequence
    - `A(n) = A(n-1) + 1` otherwise

[oeis]: https://oeis.org/A005132