A340587 a(n) is the least root of A340586(n).

2, 2, 13, 6, 7, 20, 21, 2, 5, 3, 29, 30, 34, 38, 39, 40, 12, 43, 44, 2, 7, 51, 14, 54, 5, 57, 15, 60, 61, 62, 2, 66, 67, 68, 69, 17, 72, 73, 74, 75, 18, 78, 79, 3, 19, 84, 85, 86, 87, 6, 20, 2, 92, 93, 94, 95, 21, 98, 10, 102, 22, 105, 106, 107, 108, 109, 23, 112

Offset: 1

Author

Hugo Pfoertner, Jan 14 2021

Keywords

• nonn

Examples

			a(1) = 2: A340586(1) = 4 = 2^2,
a(2) = 2: A340586(2) = 16 = 2^4,
a(3) = 13: A340586(3) = 169 = 13^2.
		

Crossrefs

Cf. A025478, A340586, A340641.

Programs

PARI

a340587(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))};
a340587(13000)

Formula

a(n) = A025478(A340586(n)).