A307664 Lexicographically earliest sequence of positive terms, such that each value, say v, appears three times at indices k, k + v and k + 2*v for some k.

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

Offset: 1

Author

Rémy Sigrist, Apr 20 2019

Keywords

• nonn

Comments

This sequence is a variant of A026242 where each value, say v, appears twice at indices k and k + v for some k.

Graphically, we have three lines.

Apparently every positive integer appears in the sequence.

Examples

			For n = 1:
- we can set a(1) = a(2) = a(3) = 1.
For n = 4:
- we can set a(4) = a(6) = a(8) = 2.
For n = 5:
- a(8) is already known, hence a(5) <> 3,
- we can set a(5) = a(9) = a(13) = 4.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program for A307664

Crossrefs

See A307667 and A307669 for other variants.

Cf. A026242.

Programs

PARI

See Links section.