A331018 Lexicographically earliest sequence of distinct positive terms that can be viewed as an irregular table where the n-th row has a(n) terms and for n > 1, T(n, k) is a multiple of k.

1, 2, 4, 3, 6, 9, 8, 5, 10, 12, 7, 14, 15, 16, 20, 18, 11, 22, 21, 24, 25, 30, 28, 32, 27, 13, 26, 33, 36, 35, 42, 49, 40, 17, 34, 39, 44, 45, 19, 38, 48, 52, 50, 54, 56, 64, 63, 60, 23, 46, 51, 68, 55, 66, 70, 72, 81, 80, 77, 84, 29, 58, 57, 76, 65, 78, 91

Offset

1,2

Comments

This sequence is a permutation of the natural numbers as each row starts with the least value not yet in the sequence.

Links

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

Index entries for sequences that are permutations of the natural numbers

Rémy Sigrist, PARI program for A331018

Example

The first terms and rows are:
  n   a(n)  row(n)
  --  ----  -------------------------------------
   1     1  [1]
   2     2  [2, 4]
   3     4  [3, 6, 9, 8]
   4     3  [5, 10, 12]
   5     6  [7, 14, 15, 16, 20, 18]
   6     9  [11, 22, 21, 24, 25, 30, 28, 32, 27]
   7     8  [13, 26, 33, 36, 35, 42, 49, 40]
   8     5  [17, 34, 39, 44, 45]
   9    10  [19, 38, 48, 52, 50, 54, 56, 64, 63, 60]
  10    12  [23, 46, 51, 68, 55, 66, 70, 72, 81, 80, 77, 84]
  11     7  [29, 58, 57, 76, 65, 78, 91]

Prog

(PARI) See Links section.

Crossrefs

See A331010 for similar sequences.

Sequence in context: A246366 A271865 A075652 * A054428 A095167 A075383

Adjacent sequences: A331015 A331016 A331017 * A331019 A331020 A331021

Keyword

nonn,look,tabf

Author

Rémy Sigrist, Jan 07 2020

Status

approved