A387103 For any n >= 2, a(n) is the number of positive values k < A386482(n-1) missing from the first n-1 terms of A386482 such that gcd(k, A386482(n-1)) != 1.

0, 0, 0, 1, 0, 0, 2, 2, 0, 1, 0, 2, 2, 0, 2, 1, 0, 0, 5, 3, 3, 1, 1, 0, 1, 0, 2, 2, 0, 1, 0, 6, 10, 8, 7, 6, 4, 2, 3, 1, 0, 1, 1, 0, 2, 4, 2, 1, 0, 1, 1, 0, 3, 3, 1, 1, 0, 8, 16, 11, 9, 11, 7, 7, 6, 3, 3, 2, 1, 0, 1, 1, 0, 0, 1, 0, 17, 31, 22, 20, 28, 24, 16

Offset: 2

Author

Rémy Sigrist, Aug 16 2025

Keywords

• nonn

Comments

This sequence gives essentially the number of candidates for A386482(n) that are less than A386482(n-1).

Examples

			The first terms, alongside A386482(n) and the corresponding k's, are:
  n   a(n)  A386482(n)  Candidates
  --  ----  ----------  --------------------
   1  N/A            1  N/A
   2     0           2  {}
   3     0           4  {}
   4     0           6  {}
   5     1           3  {3}
   6     0           9  {}
   7     0          12  {}
   8     2          10  {8, 10}
   9     2           8  {5, 8}
  10     0          14  {}
  11     1           7  {7}
  12     0          21  {}
  13     2          18  {15, 18}
  14     2          16  {15, 16}
  15     0          20  {}
  16     2          15  {5, 15}
  17     1           5  {5}
  18     0          25  {}
  19     0          30  {}
  20     5          28  {22, 24, 26, 27, 28}
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 2..10000
• Rémy Sigrist, Scatterplot of the candidates k for n = 2..1005
• Rémy Sigrist, PARI program

Crossrefs

Cf. A386482.

Programs

PARI

\\ See Links section.

Formula

a(n) = 0 iff A386482(n) > A386482(n-1).