A387613 Numbers k such that A386482(k) and A386482(k+2) are coprime.

1, 3, 6, 9, 11, 12, 14, 18, 22, 24, 26, 29, 31, 32, 41, 42, 44, 45, 47, 49, 50, 52, 55, 57, 58, 68, 70, 71, 73, 74, 76, 77, 98, 101, 102, 104, 109, 113, 115, 119, 122, 123, 124, 126, 137, 138, 142, 144, 174, 179, 187, 189, 192, 193, 196, 203, 205, 207, 234

Offset: 1

Author

Rémy Sigrist, Sep 03 2025

Keywords

• nonn
• new

Comments

For k > 1, A386482(k) and A386482(k+1) share a prime factor, however A386482(k) and A386482(k+2) may not share a prime factor. The present sequence lists those indexes.

Examples

			The first terms, alongside the first terms of A386482, are:
  k   A386482(k)  A386482(k+2)  n   a(n)
  --  ----------  ------------  --  ----
   1           1             4   1     1
   2           2             6
   3           4             3   2     3
   4           6             9
   5           3            12
   6           9            10   3     6
   7          12             8
   8          10            14
   9           8             7   4     9
  10          14            21
  11           7            18   5    11
  12          21            16   6    12
  13          18            20
  14          16            15   7    14
  15          20             5
		

Links

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

Crossrefs

Cf. A386482, A387087.

Programs

PARI

\\ See Links section.