A284434 The number of positive integer sequences of length n with no duplicate substrings of length greater than 1, every number different from its neighbors, and a minimal product (= A282169(n)).

1, 2, 1, 6, 2, 24, 6, 120, 24, 84, 192, 336, 360, 1680, 2160, 10080, 26640, 70560, 80640, 564480, 645120, 13789440, 10644480, 78382080, 43545600, 783820800, 435456000, 2264371200, 12454041600, 22643712000, 117747302400, 466460467200, 367873228800, 2391175987200, 4414478745600

Offset

1,2

Links

Table of n, a(n) for n=1..35.

Example

For n = 7 the a(7) = 6 solutions are:
  [1,4,1,3,1,2,1],
  [1,3,1,4,1,2,1],
  [1,4,1,2,1,3,1],
  [1,2,1,4,1,3,1],
  [1,3,1,2,1,4,1], and
  [1,2,1,3,1,4,1].

Crossrefs

Cf. A282169, A283557, A284431, A284435, A284436.

Sequence in context: A217955 A325703 A321898 * A306543 A243484 A181811

Adjacent sequences: A284431 A284432 A284433 * A284435 A284436 A284437

Keyword

nonn

Author

Peter Kagey, Mar 27 2017

Extensions

Terms a(8) onward from Max Alekseyev, Feb 05 2025

Status

approved