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

1,1

Links

Table of n, a(n) for n=1..68.

Formula

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

Example

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

Prog

(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)

Crossrefs

Cf. A025478, A340586, A340641.

Sequence in context: A268528 A173331 A074477 * A347080 A141575 A306738

Adjacent sequences: A340584 A340585 A340586 * A340588 A340589 A340590

Keyword

nonn

Author

Hugo Pfoertner, Jan 14 2021

Status

approved