A284435 The number of positive integer sequences of length n with no duplicate substrings (forward or backward) of length greater than 1 and a minimal product (= A282193(n)).

1, 1, 2, 2, 4, 4, 4, 48, 144, 144, 144, 2304, 2160, 8640, 8640, 8640, 161280, 806400, 806400, 806400, 38534400, 39168000, 108864000, 108864000, 2794176000, 5370624000, 10741248000, 21482496000, 286355865600, 1002245529600, 2004491059200, 4008982118400, 61212572467200, 244850289868800, 489700579737600

Offset: 1

Author

Peter Kagey, Mar 27 2017

Keywords

• nonn

Examples

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

Crossrefs

Cf. A282193, A283557, A284434, A284436, A284432.

Extensions

Terms a(11) onward from Max Alekseyev, Feb 06 2025