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A239291 Smallest k > 0 such that the products of the nonempty subsets of {k, k+1,..., k+n-1} are all distinct. 0
1, 2, 2, 2, 3, 4, 5, 7, 9, 16, 16, 22, 22, 34, 37, 46, 46, 57, 71, 79, 81, 103, 103, 106 (list; graph; refs; listen; history; text; internal format)
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: A022866 A099388 A193941 * A022869 A022865 A089150

Adjacent sequences:  A239288 A239289 A239290 * A239292 A239293 A239294

KEYWORD

nonn,more

AUTHOR

Giovanni Resta, Mar 14 2014

STATUS

approved

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Last modified May 17 12:55 EDT 2021. Contains 343971 sequences. (Running on oeis4.)