A338461 Lexicographically earliest divisibility sequence consisting only of distinct nonprime numbers.

1, 4, 6, 8, 9, 12, 10, 16, 18, 36, 14, 24, 15, 20, 54, 32, 21, 72, 22, 144, 30, 28, 25, 48, 27, 60, 90, 40, 26, 108, 33, 64, 42, 84, 180, 216, 34, 44, 120, 288, 35, 240, 38, 56, 162, 100, 39, 96, 50, 324, 126, 360, 45, 720, 252, 80, 66, 52, 46, 432, 49, 132

Offset

1,2

Comments

This sequence is a permutation of the nonprime numbers (A018252).

Links

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

Rémy Sigrist, PARI program for A338461

Index to divisibility sequences

Formula

a(p) < a(n) for any prime number p and n > p.

Example

For n = 1:
- we choose a(1) = 1.
For n = 2:
- a(2) must be divisible by a(1) = 1,
- we choose a(2) = 4.
For n = 3:
- a(3) must be divisible by a(1) = 1,
- we choose a(3) = 6.
For n = 4:
- a(4) must be divisible by a(1) = 1 and a(2) = 4,
- we choose a(4) = 8.

Prog

(PARI) See Links section.

Crossrefs

See A338219 for a similar sequence.

Cf. A018252.

Sequence in context: A202268 A084985 A068631 * A163520 A273546 A176539

Adjacent sequences: A338458 A338459 A338460 * A338462 A338463 A338464

Keyword

nonn,look

Author

Rémy Sigrist, Jan 31 2021

Status

approved