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A340641
a(n) is the least root of A340640(n).
5
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, 10, 2, 33, 35, 6, 11, 37, 41, 42, 45, 46, 3, 13, 47, 48, 50, 52, 53, 55, 56, 58, 59, 63, 65, 70, 71, 76, 77, 80, 82, 83, 88, 89, 90, 91, 96, 97, 99, 101, 103, 104, 110
OFFSET
1,1
FORMULA
a(n) = A025478(A340640(n)).
EXAMPLE
a(1) = 2: A340640(1) = 4 = 2^2;
a(2) = 3: A340640(2) = 9 = 3^2;
a(3) = 5: A350640(3) = 25 = 5^2;
a(4) = 3: A340640(4) = 27 = 3^3.
PROG
(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))};
a340641(13000)
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Jan 14 2021
STATUS
approved