A282170 - OEIS

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, 2, 6, 6, 24, 48, 120, 240, 1440, 2880, 10080

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OFFSET

1,2

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].

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

CROSSREFS

Cf. A282164, A282169.

Cf. A282167 is the sum analog.

Sequence in context: A325803 A130865 A327630 * A105725 A005226 A087310

Adjacent sequences: A282167 A282168 A282169 * A282171 A282172 A282173

KEYWORD

nonn,more

AUTHOR

Peter Kagey, Feb 07 2017

STATUS

approved