A384970 a(n) is the length of the largest run of consecutive terms of A386482 containing A386482(n) and sharing a common prime factor.

0, 3, 3, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 3, 3, 3, 4, 4, 4, 4, 3, 3, 8, 8, 8, 8, 8, 8, 8, 8, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 3, 3, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 3, 3, 3, 3, 3, 3, 3, 3, 22, 22, 22, 22, 22

Offset

1,2

Comments

a(1) = 0 by convention as A386482(1) = 1 has no prime factor.

Note that there might be several largest runs (necessarily with distinct common prime factors) for a given index n: for example, for n = 7, A386482(7) = 12 belongs to [6, 3, 9, 12] (with common prime factor 3) and to [12, 10, 8, 14] (with common prime factor 2).

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10117

Rémy Sigrist, PARI program

Example

The first terms are:
  n   a(n)  A386482(n)  Largest run
  --  ----  ----------  ---------------
   1     0           1  []
   2     3           2  [2,4,6]
   3     3           4  [2,4,6]
   4     4           6  [6,3,9,12]
   5     4           3  [6,3,9,12]
   6     4           9  [6,3,9,12]
   7     4          12  [6,3,9,12]
   8     4          10  [12,10,8,14]
   9     4           8  [12,10,8,14]
  10     4          14  [12,10,8,14]
  11     3           7  [14,7,21]
  12     3          21  [14,7,21]
  13     3          18  [18,16,20]
  14     3          16  [18,16,20]
  15     5          20  [20,15,5,25,30]
  16     5          15  [20,15,5,25,30]

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A386482, A387542.

Sequence in context: A298199 A282623 A090589 * A163400 A090972 A318241

Adjacent sequences: A384967 A384968 A384969 * A384971 A384972 A384973

Keyword

nonn

Author

Rémy Sigrist, Sep 07 2025

Status

approved