A382377 Lexicographically earliest sequence of distinct positive integers such that the number of distinct prime factors of n and a(n) differ exactly by one.

2, 1, 6, 10, 12, 3, 14, 15, 18, 4, 20, 5, 21, 7, 8, 22, 24, 9, 26, 11, 13, 16, 28, 17, 33, 19, 34, 23, 35, 36, 38, 39, 25, 27, 29, 30, 40, 31, 32, 37, 44, 45, 46, 41, 42, 43, 48, 47, 50, 49, 53, 59, 51, 60, 61, 64, 66, 67, 52, 54, 55, 70, 71, 56, 73, 57, 58

Offset

1,1

Comments

A self-inverse permutation of the positive integers.

Links

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

Rémy Sigrist, PARI program

Index entries for sequences that are permutations of the natural numbers

Example

The initial terms are:
  n   a(n)  A001221(n)  A001221(a(n))
  --  ----  ----------  -------------
   1     2           0              1
   2     1           1              0
   3     6           1              2
   4    10           1              2
   5    12           1              2
   6     3           2              1
   7    14           1              2
   8    15           1              2
   9    18           1              2
  10     4           2              1
  11    20           1              2
  12     5           2              1
  13    21           1              2
  14     7           2              1
  15     8           2              1

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A001221, A382375, A382376.

Sequence in context: A069114 A380531 A173773 * A305512 A121927 A200265

Adjacent sequences: A382374 A382375 A382376 * A382378 A382379 A382380

Keyword

nonn

Author

Rémy Sigrist, Mar 23 2025

Status

approved