A336200 Lexicographically earliest sequence of distinct terms such that every integer k appears twice, at distance a(k).

1, 1, 2, 2, 3, 4, 3, 4, 5, 6, 8, 5, 7, 6, 8, 7, 9, 10, 11, 12, 13, 9, 14, 10, 12, 15, 11, 13, 14, 16, 17, 18, 19, 15, 20, 21, 16, 23, 22, 17, 24, 18, 25, 19, 26, 27, 20, 22, 21, 28, 24, 23, 29, 30, 25, 31, 27, 32, 33, 26, 35, 34, 28, 36, 38, 37, 29, 39, 40, 30

Offset: 1

Author

Rémy Sigrist, Jul 11 2020

Keywords

• nonn

Comments

This sequence combines features of A001462 and of A026242.

Examples

			For n = 1:
- we can choose a(1) = 1,
- and then a(1+a(1)) = a(2) = 1.
For n = 3:
- we can choose a(3) = 2,
- and then a(3+a(2)) = a(4) = 2.
For n = 5:
- we can choose a(5) = 3,
- and then a(5+a(3)) = a(7) = 3.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program for A336200

Crossrefs

Cf. A001462, A026242.

Programs

PARI

See Links section.