A340699 a(n) is the position of n^3 in the list of perfect powers.

1, 3, 7, 11, 15, 20, 26, 31, 36, 41, 47, 53, 61, 68, 76, 82, 89, 96, 103, 112, 121, 129, 137, 145, 153, 162, 171, 180, 189, 198, 207, 217, 226, 236, 246, 255, 265, 275, 285, 295, 306, 317, 328, 339, 350, 361, 374, 385, 396, 407, 420, 431, 443, 455, 468, 481, 494

Offset

1,2

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Mathematica

A340699[n_] :=
  First @@ Position[
    Join[{1},
     Select[Range[n^3], GCD @@ FactorInteger[#][[All, 2]] > 1 &]],
    n^3];
Table[A340699[n], {n, 1, 57}] (* Robert P. P. McKone, Jan 17 2021 *)

Prog

(PARI) ispwr(n) = ispower(n) || (n==1); \\ A001597
Vec(select(x->ispower(x, 3), select(ispwr, [1..2*10^5]), 1)) \\ Michel Marcus, Jan 18 2021

Crossrefs

Cf. A000578, A001597, A340698.

Sequence in context: A310212 A310213 A109507 * A160802 A170888 A182838

Adjacent sequences: A340696 A340697 A340698 * A340700 A340701 A340702

Keyword

nonn

Author

Hugo Pfoertner, Jan 17 2021

Status

approved