A375615 Lexicographically earliest sequence of distinct positive integers such that for any n > 0, n * a(n) belongs to A055932.

1, 2, 4, 3, 6, 5, 30, 8, 10, 9, 210, 12, 2310, 15, 14, 16, 30030, 18, 510510, 21, 20, 105, 9699690, 24, 36, 1155, 32, 45, 223092870, 7, 6469693230, 27, 70, 15015, 42, 25, 200560490130, 255255, 770, 48, 7420738134810, 35, 304250263527210, 315, 28, 4849845

Offset: 1

Author

Rémy Sigrist, Aug 21 2024

Keywords

• nonn

Comments

This sequence is a self-inverse permutation of the positive integers.

The n-th term is a multiple of A083720(n).

Examples

			The first terms, alongside the prime factors of n*a(n), are:
  n   a(n)  Prime factors
  --  ----  --------------------
   1     1  {}
   2     2  {2}
   3     4  {2, 3}
   4     3  {2, 3}
   5     6  {2, 3, 5}
   6     5  {2, 3, 5}
   7    30  {2, 3, 5, 7}
   8     8  {2}
   9    10  {2, 3, 5}
  10     9  {2, 3, 5}
  11   210  {2, 3, 5, 7, 11}
  12    12  {2, 3}
  13  2310  {2, 3, 5, 7, 11, 13}
  14    15  {2, 3, 5, 7}
  15    14  {2, 3, 5, 7}
		

Links

• Rémy Sigrist, PARI program
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A055932, A083720, A375579.

Programs

PARI

\\ See Links section.