A260060 Least number such that exactly n iterations of A034690 are required to reach one of the fixed points, 1 or 15.

1, 8, 7, 4, 3, 2, 19, 12, 6, 5, 13, 9, 10, 16, 30, 18, 34, 36, 66, 162, 924, 71820

Offset

0,2

Comments

Apart from the initial term a(1), the same as A094501.

Links

Table of n, a(n) for n=0..21.

E. Angelini et al., List the dividers, sum the digits, SeqFan list, Nov. 2015

Example

The orbits are:
  {1},
  {8, 15},
  {7, 8, 15},
  {4, 7, 8, 15},
  {3, 4, 7, 8, 15},
  {2, 3, 4, 7, 8, 15},
  {19, 11, 3, 4, 7, 8, 15},
  {12, 19, 11, 3, 4, 7, 8, 15},
  {6, 12, 19, 11, 3, 4, 7, 8, 15},
  {5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {10, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {16, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {34, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {36, 46, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {66, 36, 46, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {162, 66, 36, 46, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {924, 168, 102, 36, 46, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15},
  {71820, 1104, 168, 102, 36, 46, 18, 30, 27, 22, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15}

Prog

(PARI) a(n)=for(k=1, 9e9, A086793(k)==n&&return(k))

Crossrefs

Cf. A034690, A086793, A094501, A095347.

Sequence in context: A158288 A193716 A268046 * A260800 A196914 A072102

Adjacent sequences: A260057 A260058 A260059 * A260061 A260062 A260063

Keyword

nonn,base

Author

M. F. Hasler, Nov 08 2015

Status

approved