A282169 a(n) is the minimal product of a positive integer sequence of length n with no duplicate substrings of length greater than 1, and every number different from its neighbors.

1, 2, 2, 6, 6, 24, 24, 120, 120, 576, 720

Offset

1,2

Comments

Examples:

[1,1] is not a valid sequence because 1 is self-adjacent.

[1,2,3,1,2] is not valid because the substring [1,2] appears twice.

Links

Table of n, a(n) for n=1..11.

Example

  a(1)  = 1   via [1];
  a(2)  = 2   via [1,2];
  a(3)  = 2   via [1,2,1];
  a(4)  = 6   via [1,2,1,3];
  a(5)  = 6   via [1,2,1,3,1];
  a(6)  = 24  via [1,2,1,3,1,4];
  a(7)  = 24  via [1,2,1,3,1,4,1];
  a(8)  = 120 via [1,2,1,3,1,4,1,5];
  a(9)  = 120 via [1,2,1,3,1,4,1,5,1];
  a(10) = 576 via [1,2,1,3,1,4,2,3,4,1];
  a(11) = 720 via [1,2,1,3,1,4,1,5,1,6,1].

Crossrefs

Cf. A282164.

Cf. A282166 is the sum analog.

Sequence in context: A135401 A129881 A132369 * A081123 A056038 A076929

Adjacent sequences: A282166 A282167 A282168 * A282170 A282171 A282172

Keyword

nonn,more

Author

Peter Kagey, Feb 07 2017

Status

approved