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A299440 Lexicographically earliest sequence of distinct positive terms such that, for any n > 0, if prime(k) divides a(n) then k divides a(n+1) (where prime(k) denotes the k-th prime). 1
1, 2, 3, 4, 5, 6, 8, 7, 12, 10, 9, 14, 16, 11, 15, 18, 20, 21, 24, 22, 25, 27, 26, 30, 36, 28, 32, 13, 42, 40, 33, 50, 39, 48, 34, 35, 60, 54, 38, 56, 44, 45, 66, 70, 72, 46, 63, 52, 78, 84, 64, 17, 49, 68, 77, 80, 51, 98, 76, 88, 55, 75, 90, 96, 58, 100, 57 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

In other words, for any n > 0, A290103(a(n)) divides a(n+1).

See also A299441 (where we consider only least prime factors) and A299442 (where we consider only greatest prime factors).

LINKS

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

Rémy Sigrist, PARI program for A299440

EXAMPLE

The first terms, alongside A290103(a(n)), are:

  n     a(n)  A290103(a(n))

  --    ----  -------------

   1       1      1

   2       2      1

   3       3      2

   4       4      1

   5       5      3

   6       6      2

   7       8      1

   8       7      4

   9      12      2

  10      10      3

  11       9      2

  12      14      4

  13      16      1

  14      11      5

  15      15      6

  16      18      2

  17      20      3

  18      21      4

  19      24      2

  20      22      5

PROG

(PARI) See Links section.

CROSSREFS

Cf. A290103, A299441, A299442.

Sequence in context: A274607 A262374 A299442 * A145518 A256221 A210253

Adjacent sequences:  A299437 A299438 A299439 * A299441 A299442 A299443

KEYWORD

nonn

AUTHOR

Rémy Sigrist, Feb 10 2018

STATUS

approved

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Last modified November 19 04:22 EST 2018. Contains 317333 sequences. (Running on oeis4.)