A239291 Smallest k > 0 such that the products of the nonempty subsets of {k, k+1,..., k+n-1} are all distinct.

1, 2, 2, 2, 3, 4, 5, 7, 9, 16, 16, 22, 22, 34, 37, 46, 46, 57, 71, 79, 81, 103, 103, 106

Offset

1,2

Links

Table of n, a(n) for n=1..24.

Formula

a(n) >= A239276(n).

Example

a(5) = 3 because the range {1,...,5} is ruled out by 1*2=2, the range {2,...,6} by 2*3 = 6 and all 31 subsets of {3,...,7} give a distinct product.

Mathematica

a[1]=1; a[n_] := a[n] = Block[{k = a[n-1]}, While[Min@ Differences@ Sort[Times @@@ Rest@ Subsets@ Range[k, n+k-1]] == 0, k++]; k]; Array[a, 16]

Crossrefs

Cf. A239276, A239277.

Sequence in context: A350701 A099388 A193941 * A022869 A359319 A357384

Adjacent sequences: A239288 A239289 A239290 * A239292 A239293 A239294

Keyword

nonn,more

Author

Giovanni Resta, Mar 14 2014

Status

approved