A338243 a(0) = 0, a(n) = A338241(2*n-1) for any n > 0.

0, 1, 3, 2, 4, 9, 8, 7, 6, 5, 10, 12, 11, 13, 27, 26, 25, 24, 23, 19, 21, 20, 22, 18, 17, 16, 15, 14, 28, 30, 29, 31, 36, 35, 34, 33, 32, 37, 39, 38, 40, 81, 80, 79, 78, 77, 73, 75, 74, 76, 72, 71, 70, 69, 68, 55, 57, 56, 58, 63, 62, 61, 60, 59, 64, 66, 65, 67

Offset: 0

Author

Rémy Sigrist, Oct 18 2020

Keywords

• nonn

Comments

This sequence is a self-inverse permutation of the nonnegative integers.

Examples

			a(7) = A338241(13) = 7.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..6560
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A338241, A338242.

Programs

PARI

b(n) = { if (n==0, return (0), my (d=n%3, m=n\3); if (d==0, 3*b(m), d==1, 1-3*b(m), 3*b(m)-1)) }
a(n) = if (n==0, 0, b(2*n-1))