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%I #9 Dec 08 2020 21:16:04
%S 1,1,1,1,3,3,5,5,11,25,41,41,80,80,144,284,568,568,1147,1147,2339,
%T 4667,8763,8763,17548,35196,67964,135918,273806,273806,548956,548956,
%U 1097974,2194294,4291446,8608698,17216783,17216783,33993999,67979983,135956742
%N Number of subsets of {2..n} such that the product of the elements is a perfect power.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PerfectPower.html">Perfect Power</a>
%F a(p) = a(p-1) for p prime.
%e 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}.
%Y Cf. A001597, A089819, A320322, A339554.
%K nonn
%O 0,5
%A _Ilya Gutkovskiy_, Dec 08 2020
%E a(25)-a(40) from _Alois P. Heinz_, Dec 08 2020
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