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A282167
a(n) is the minimal sum 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.
5
1, 3, 6, 7, 11, 13, 17, 19, 25, 27
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 the substring [1,2] appears twice (once forward and once backward).
EXAMPLE
a(1) = 1 via [1];
a(2) = 3 via [1,2];
a(3) = 6 via [1,2,3];
a(4) = 7 via [1,2,3,1];
a(5) = 11 via [1,2,3,1,4];
a(6) = 13 via [1,2,3,1,4,2];
a(7) = 17 via [1,2,3,1,4,5,1];
a(8) = 19 via [1,2,3,1,4,2,5,1];
a(9) = 25 via [1,2,3,1,4,2,5,1,6];
a(10) = 27 via [1,2,3,1,4,2,5,1,6,2].
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Peter Kagey, Feb 07 2017
STATUS
approved