A331985 - OEIS

A331985

a(n) is the least positive k such that n AND floor(n/k) = 0 (where AND denotes the bitwise AND operator).

1, 2, 2, 4, 2, 2, 4, 8, 2, 2, 2, 12, 4, 5, 8, 16, 2, 2, 2, 4, 2, 2, 12, 24, 4, 4, 5, 6, 8, 10, 16, 32, 2, 2, 2, 4, 2, 2, 4, 40, 2, 2, 2, 9, 12, 16, 24, 48, 4, 4, 4, 4, 5, 5, 6, 56, 8, 9, 10, 12, 16, 21, 32, 64, 2, 2, 2, 4, 2, 2, 4, 8, 2, 2, 2, 16, 4, 26, 40

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OFFSET

0,2

COMMENTS

This sequence has similarities with A261891; here we divide and round down, there we multiply, in order to obtain a number with no common bit with the original.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..8192

FORMULA

a(n) = 2 iff n is a positive Fibbinary number (A003714).

EXAMPLE

For n = 3:

- 3 AND floor(3/1) = 3,

- 3 AND floor(3/2) = 1,

- 3 AND floor(3/3) = 1,

- 3 AND floor(3/4) = 0,

- hence a(3) = 4.

PROG