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A339497 Numbers k such that (k*i)^(1/4) is an integer for some i in 1 <= i <= k. 2
1, 4, 8, 9, 16, 25, 27, 32, 36, 48, 49, 54, 64, 72, 81, 100, 108, 121, 125, 128, 144, 162, 169, 192, 196, 200, 216, 225, 243, 250, 256, 288, 289, 324, 343, 361, 375, 384, 392, 400, 405, 432, 441, 484, 486, 500, 512, 529, 567, 576, 625, 640, 648, 675, 676, 686, 729, 768 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

9 is in the sequence since (9*9)^(1/4) = 3 (an integer), with 1 <= 9 <= 9.

MAPLE

filter:= proc(n) local F, x, t;

  F:= ifactors(n)[2];

  x:= mul(t[1]^(-t[2] mod 4), t=F);

  x <= n

end proc:

select(filter, [$1..1000]); # Robert Israel, Dec 29 2020

MATHEMATICA

Table[If[Sum[1 - Ceiling[(n*k)^(1/4)] + Floor[(n*k)^(1/4)], {k, n}] > 0, n, {}], {n, 500}] // Flatten

CROSSREFS

Cf. A339462.

Sequence in context: A109422 A158804 A341645 * A080366 A001694 A317102

Adjacent sequences:  A339494 A339495 A339496 * A339498 A339499 A339500

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Dec 27 2020

STATUS

approved

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Last modified May 18 07:26 EDT 2021. Contains 343995 sequences. (Running on oeis4.)