A100281 a(n) = A099896(A099896(n)).

0, 1, 2, 3, 5, 4, 7, 6, 10, 11, 8, 9, 15, 14, 13, 12, 21, 20, 23, 22, 16, 17, 18, 19, 31, 30, 29, 28, 26, 27, 24, 25, 42, 43, 40, 41, 47, 46, 45, 44, 32, 33, 34, 35, 37, 36, 39, 38, 63, 62, 61, 60, 58, 59, 56, 57, 53, 52, 55, 54, 48, 49, 50, 51, 84, 85, 86, 87, 81, 80, 83, 82, 94

Offset: 0

Author

Reinhard Zumkeller, Nov 11 2004

Keywords

• nonn
• look

Comments

Permutation of the natural numbers with inverse A100282;

A064707(n) = a(n) for n<64.

Links

• Ivan Neretin, Table of n, a(n) for n = 0..8191
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A099896, A064707, A100282.

Programs

Python

def A100281(n): return n^(m:=n>>2)^(m>>2) # Chai Wah Wu, Jan 19 2023

Formula

a(n) = n XOR floor(n/4) XOR floor(n/16). - Ivan Neretin, Sep 06 2017