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

1,4

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.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, PARI program for A307664

Example

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.

Prog

(PARI) See Links section.

Crossrefs

See A307667 and A307669 for other variants.

Cf. A026242.

Sequence in context: A347184 A019294 A238262 * A057037 A076920 A183225

Adjacent sequences: A307661 A307662 A307663 * A307665 A307666 A307667

Keyword

nonn

Author

Rémy Sigrist, Apr 20 2019

Status

approved