A169748 A variation on Recamán's sequence A005132: see Comments for definition.

1, 3, 2, 5, 9, 4, 10, 8, 15, 7, 16, 6, 17, 14, 26, 13, 27, 12, 28, 11, 29, 25, 20, 39, 19, 40, 18, 41, 35, 59, 34, 60, 33, 61, 32, 62, 31, 24, 56, 23, 57, 22, 58, 21, 59, 51, 42, 81, 71, 111, 70, 112, 69, 113, 68, 114, 67, 115, 66, 55, 43, 30, 80, 131, 79, 65, 50, 103, 49, 104

Offset: 1

Author

Rodolfo Kurchan, Apr 08 2010

Keywords

• nonn

Comments

Sequences A169748-A169752 have the same structure. We start with two sequences A and B. Sequence A is taken to be 1,2,3,4,5,6,7,..., while sequence B varies.

Here sequence B is also 1,2,3,4,5,6,7,....

We start with the first term of sequence A (which is 1).

To extend the sequence, we first try to subtract the next term of A from the current term, but that is allowed only if the result is a positive number not already in the sequence.

If that fails, we next try to subtract the next term of B from the current term, but again that is allowed only if the result is a positive number not already in the sequence.

Finally, if that fails, we add the next term of A to the current term (this may produce repeated terms, but that is allowed at this step).

Examples

			Start with 1 from A,
add 2 from A getting 3,
subtract 1 from B getting 2,
add 3 from A getting 5,
add 4 from A getting 9,
subtract 5 from A getting 4,
add 6 from A getting 10,
subtract 2 from B getting 8,
add 7 from A getting 15,
add 9 from A getting 16,
subtract 10 from A getting 6,
add 11 from A getting 17,
subtract 3 from B getting 14,
add 12 from A getting 26,
subtract 13 from A getting 13, ...
		

Crossrefs

Cf. A005132, A169749-A169752, A169755.

Extensions

Extended by D. S. McNeil, May 09 2010