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%I #5 Jan 14 2021 15:03:11
%S 2,3,5,3,2,6,7,2,3,10,11,5,2,12,14,15,3,2,17,18,19,22,23,24,26,28,31,
%T 10,2,33,35,6,11,37,41,42,45,46,3,13,47,48,50,52,53,55,56,58,59,63,65,
%U 70,71,76,77,80,82,83,88,89,90,91,96,97,99,101,103,104,110
%N a(n) is the least root of A340640(n).
%F a(n) = A025478(A340640(n)).
%e a(1) = 2: A340640(1) = 4 = 2^2;
%e a(2) = 3: A340640(2) = 9 = 3^2;
%e a(3) = 5: A350640(3) = 25 = 5^2;
%e a(4) = 3: A340640(4) = 27 = 3^3.
%o (PARI) a340641(limit)={my(p2=999, p1=2, n2=1, n1=4); for(n=5, limit, my(p0=ispower(n)); if(p0>1, if(p2+p0>4, print1(round(n1^(1/p1)), ", ")); n2=n1; n1=n; p2=p1; p1=p0))};
%o a340641(13000)
%Y Cf. A025478, A340587, A340640.
%K nonn
%O 1,1
%A _Hugo Pfoertner_, Jan 14 2021
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