cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A381405 a(0) = 0; for n > 0, a(n) is the smallest unused number such that a(n) AND a(n-1) = 0, where AND is the binary AND operation, while the binary weight of a(n) does not equal that of a(n-1).

Original entry on oeis.org

0, 1, 6, 8, 3, 4, 9, 2, 5, 16, 7, 24, 32, 10, 21, 34, 13, 18, 37, 64, 11, 20, 35, 12, 19, 36, 25, 66, 28, 33, 14, 17, 38, 65, 22, 40, 23, 72, 39, 80, 15, 48, 67, 60, 128, 26, 68, 27, 96, 29, 98, 129, 30, 97, 130, 41, 86, 136, 49, 78, 144, 42, 85, 138, 53, 74, 132, 43, 84, 139, 52, 75, 148, 99, 140, 51, 76, 147, 44, 83, 160, 31, 192, 45, 82, 141, 50, 77, 146, 101
Offset: 0

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Author

Scott R. Shannon, Feb 22 2025

Keywords

Comments

In the first 100000 terms the fixed points are 0, 1, 28, 76, 543, 1580, although more likely exist.

Examples

			a(3) = 8 = 1000_2 as 8 is unused and a(2) = 6 = 110_2, and 1000_2 AND 110_2 = 0 while the binary weights of 8 and 6 are 1 and 2 respectively.
		

Crossrefs

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