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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
OFFSET
1,2
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
Sequence in context: A350701 A099388 A193941 * A022869 A359319 A357384
KEYWORD
nonn,more
AUTHOR
Giovanni Resta, Mar 14 2014
STATUS
approved