A340641 a(n) is the least root of A340640(n).

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

Author

Hugo Pfoertner, Jan 14 2021

Keywords

• nonn

Examples

			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.
		

Crossrefs

Cf. A025478, A340587, A340640.

Programs

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)

Formula

a(n) = A025478(A340640(n)).