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A392322
Number of coverings of [n] by 1-tuples, 2-tuples, ..., n-tuples where each entry is chosen from the subsets of [n].
1
1, 10, 371, 53108, 29405577, 63422514894, 536842525103887, 17946027593293876456, 2380248400260600171166613, 1256540596610637930077566092098, 2645496803167571992523450535629589723, 22240912657758659268957594752722686275423964
OFFSET
1,2
FORMULA
a(n) = Sum_{k=1..n} (2^k - 1)^n.
a(n) = Sum_{k=1..n} A092477(n,k).
a(n) = Sum_{k=1..n} A329943(k,n).
a(n) = Sum_{k=1..n} A245789(n,k).
EXAMPLE
The a(2) = 1 + 9 = 10:
({1,2}) ({},{1,2})
({1},{2})
({1},{1,2})
({2},{1,2})
({2},{1})
({1,2},{})
({1,2},{1})
({1,2},{2})
({1,2},{1,2}).
MATHEMATICA
a[n_] := a[n] = Sum[(2^k - 1)^n, {k, 1, n}]; Table[a[n], {n, 1, 15}]
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved