A391066 a(n) is the last term of the map x -> A087207(x) starting with A019565(n) before reaching 1 or -1 if 1 is never reached.

2, 2, 2, 4, 4, 2, 8, 8, 2, 4, 16, 2, 32, 2, 2, 16, 64, 2, 128, 4, 4, 64, 256, 2, 4, 2, 2, 2, 512, 8, 1024, 32, 2, 2, 2, 2, 2048

Offset

1,1

Comments

The position of the term in the map is given by A288569(n).

Links

Table of n, a(n) for n=1..37.

Example

The table of the map is:
  1:   2  1
  2:   3  2  1
  3:   6  3  2  1
  4:   5  4  1
  5:  10  5  4  1
  6:  15  6  3  2  1
  7:  30  7  8  1
  8:   7  8  1
  9:  14  9  2  1
  10: 21 10  5  4  1
  11: 42 11 16  1
  12: 35 12  3  2  1
  13: 70 13 32  1

Crossrefs

Cf. A087207, A019565, A288569, A391067.

Sequence in context: A130453 A376690 A259981 * A070705 A216326 A381749

Adjacent sequences: A391063 A391064 A391065 * A391067 A391068 A391069

Keyword

nonn,hard,more

Author

Flávio V. Fernandes, Nov 27 2025

Status

approved