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A339555
Number of subsets of {2..n} such that the product of the elements is a perfect power.
1
1, 1, 1, 1, 3, 3, 5, 5, 11, 25, 41, 41, 80, 80, 144, 284, 568, 568, 1147, 1147, 2339, 4667, 8763, 8763, 17548, 35196, 67964, 135918, 273806, 273806, 548956, 548956, 1097974, 2194294, 4291446, 8608698, 17216783, 17216783, 33993999, 67979983, 135956742
OFFSET
0,5
LINKS
Eric Weisstein's World of Mathematics, Perfect Power
FORMULA
a(p) = a(p-1) for p prime.
EXAMPLE
a(8) = 11 subsets: {}, {4}, {8}, {2, 4}, {2, 8}, {4, 8}, {2, 3, 6}, {2, 4, 8}, {3, 6, 8}, {2, 3, 4, 6} and {3, 4, 6, 8}.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Dec 08 2020
EXTENSIONS
a(25)-a(40) from Alois P. Heinz, Dec 08 2020
STATUS
approved