A174204 Scan the sequence of natural numbers, written in base 2, from left to right, delete each 2nd, 4th, 6th etc occurrence of digit 0 and each 2nd, 4th, 6th etc occurrence of digit 1. The sequence are the base-10 residuals.

0, 1, 1, 2, 1, 1, 1, 4, 1, 2, 1, 2, 5, 1, 3, 4, 1, 1, 1, 4, 5, 2, 3, 4, 5, 2, 3, 6, 5, 3, 3, 8

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Mar 15 2010

Keywords

• easy
• nonn
• base
• less

Comments

Deleting the even occurrences of 0 and the odd occurrences of 1, we get the same sequence apart from the initial three terms 0,1,1 replaced by 0.

Examples

			Numbers in base 2 (A007088):
0, 1, 10, 11, 100, 101, 110, 111, 1000.....
Delete 2nd, 4th, 6th,.. (even) occurrence of 0 (replaced by ~):
0, 1, 1~, 11, 10~, 101, 11~, 111, 10~0
Delete 2nd, 4th 6th,... (even) occurrence of 1 (replaced by ~):
0, 1, ~~, 1~, 10~, ~01, ~1~, ~1~, 10~0
The numbers left are:
0, 1, 1, 10, 1, 1, 1, 100,  and in base 10: 0, 1, 1, 2, 1, 1, 1, 4, ....as shown by a(n).
		

Crossrefs

Cf. A174203, A174205-A174210.