A307667 Lexicographically earliest sequence of positive terms, such that each value, say v, appears four times at indices k, k + v, k + 2*v and k + 3*v for some k.

1, 1, 1, 1, 2, 4, 2, 7, 2, 4, 2, 8, 6, 4, 7, 11, 9, 4, 6, 8, 12, 7, 14, 15, 6, 9, 11, 8, 7, 10, 6, 16, 12, 18, 9, 8, 14, 11, 15, 10, 17, 13, 20, 9, 12, 25, 19, 16, 11, 10, 14, 18, 3, 15, 13, 3, 12, 17, 3, 10, 23, 3, 20, 16, 14, 19, 5, 13, 15, 18, 25, 5, 21, 24

Offset

1,5

Comments

This sequence is a variant of A307664.

Graphically, we have four wavy lines.

Apparently every positive integer appears in the sequence.

Links

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

Rémy Sigrist, Colored scatterplot of the first 250000 terms (where the color is based on the ordinal transform of the sequence)

Rémy Sigrist, PARI program for A307667

Example

For n = 1:
- we can set a(1) = a(2) = a(3) = a(4) = 1.
For n = 5:
- we can set a(5) = a(7) = a(9) = a(11) = 2.
For n = 6:
- a(9) is already known, hence a(6) <> 3,
- we can set a(6) = a(10) = a(14) = a(18) = 4.

Prog

(PARI) See Links section.

Crossrefs

Cf. A026242, A307664.

Sequence in context: A296471 A021416 A094756 * A228367 A110925 A214789

Adjacent sequences: A307664 A307665 A307666 * A307668 A307669 A307670

Keyword

nonn

Author

Rémy Sigrist, Apr 20 2019

Status

approved