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A282170 a(n) is the minimal product of a positive integer sequence of length n with no duplicate substrings (forward or backward) of length greater than 1, and no self-adjacent terms. 1
1, 2, 6, 6, 24, 48, 120, 240, 1440, 2880, 10080 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Examples:

  [1,1] is invalid because 1 is self-adjacent.

  [1,2,3,1,2] is invalid because the substring [1,2] appears twice.

  [1,2,1] is invalid because because the substring [1,2] appears twice (once forward and once backward).

LINKS

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

EXAMPLE

  a(1)  = 1     via [1];

  a(2)  = 2     via [1,2];

  a(3)  = 6     via [1,2,3];

  a(4)  = 6     via [1,2,3,1];

  a(5)  = 24    via [1,2,3,1,4];

  a(6)  = 48    via [1,2,3,1,4,2];

  a(7)  = 120   via [1,2,3,1,4,5,1];

  a(8)  = 240   via [1,2,3,1,4,2,5,1];

  a(9)  = 1440  via [1,2,3,1,4,2,5,1,6];

  a(10) = 2880  via [1,2,3,1,4,2,5,1,6,2];

  a(11) = 10080 via [1,2,3,1,4,2,5,1,6,7,1].

CROSSREFS

Cf. A282164, A282169.

Cf. A282167 is the sum analog.

Sequence in context: A242527 A304680 A130865 * A105725 A005226 A087310

Adjacent sequences:  A282167 A282168 A282169 * A282171 A282172 A282173

KEYWORD

nonn,more

AUTHOR

Peter Kagey, Feb 07 2017

STATUS

approved

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Last modified October 17 22:48 EDT 2018. Contains 316297 sequences. (Running on oeis4.)