A321767 Reverse runs of nonzero digits in ternary expansion of n and convert back to decimal.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 19, 12, 13, 14, 15, 16, 17, 18, 11, 20, 21, 22, 23, 24, 25, 26, 27, 28, 55, 30, 37, 46, 57, 64, 73, 36, 31, 58, 39, 40, 41, 42, 43, 44, 45, 32, 59, 48, 49, 50, 51, 52, 53, 54, 29, 56, 33, 38, 47, 60, 65, 74, 63, 34, 61, 66, 67

Offset: 0

Author

Rémy Sigrist, Nov 18 2018

Keywords

• nonn
• base
• look

Comments

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

Examples

			For n = 11111:
- the ternary representation of 11111 is "120020112",
- we have three runs of nonzero digits: "12", "2" and "112",
- we replace the first by the third, the third by the first and the second remains in place,
- the result is: "112002012",
- and a(11111) = 10265.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..19683
• Rémy Sigrist, PARI program for A321767
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

See A321726 for a similar sequence.

Programs

PARI

See Links section.

Formula

a(3 * n) = 3 * a(n).