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A338444 Lexicographically earliest sequence of distinct squarefree numbers such that for any prime p, any run of consecutive multiples of p has length exactly 2. 4
1, 2, 6, 3, 5, 10, 14, 7, 11, 22, 26, 13, 15, 30, 34, 17, 19, 38, 42, 21, 23, 46, 58, 29, 31, 62, 66, 33, 35, 70, 74, 37, 39, 78, 82, 41, 43, 86, 94, 47, 51, 102, 106, 53, 55, 110, 114, 57, 59, 118, 122, 61, 65, 130, 134, 67, 69, 138, 142, 71, 73, 146, 154, 77 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence is a squarefree variant of A280864.

Conjecture: this sequence is a permutation of the squarefree numbers (A005117).

LINKS

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

Rémy Sigrist, C program for A338444

EXAMPLE

The first terms, alongside their prime factors, are:

  n   a(n)  Prime factors

  --  ----  -------------

   1     1

   2     2  2

   3     6  2 3

   4     3    3

   5     5      5

   6    10  2   5

   7    14  2     7

   8     7        7

   9    11          11

  10    22  2       11

  11    26  2         13

  12    13            13

  13    15    3 5

  14    30  2 3 5

  15    34  2           17

  16    17              17

PROG

(C) See Links section.

CROSSREFS

Cf. A005117, A280864, A338441.

Sequence in context: A064433 A163338 A323335 * A139384 A083481 A177209

Adjacent sequences:  A338441 A338442 A338443 * A338445 A338446 A338447

KEYWORD

nonn

AUTHOR

Rémy Sigrist, Oct 28 2020

STATUS

approved

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Last modified May 8 11:51 EDT 2021. Contains 343666 sequences. (Running on oeis4.)