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A338387 Numbers k such that there are no biquadratefree powerful numbers (A338325) between k^2 and (k+1)^2. 6

%I #10 Oct 24 2020 04:03:42

%S 1,3,4,6,7,9,12,13,15,16,17,20,21,23,24,26,27,28,29,30,32,34,35,38,39,

%T 40,41,43,44,45,47,49,50,54,56,60,61,62,63,64,66,68,69,71,74,75,76,77,

%U 79,80,81,83,84,85,86,89,90,91,95,97,99,100,101,105,106,107

%N Numbers k such that there are no biquadratefree powerful numbers (A338325) between k^2 and (k+1)^2.

%C Positions of 0's in A338326.

%C The asymptotic density of this sequence is 0.623265038... (Dehkordi, 1998).

%H Amiram Eldar, <a href="/A338387/b338387.txt">Table of n, a(n) for n = 1..10000</a>

%H Massoud H. Dehkordi, <a href="https://hdl.handle.net/2134/12177">Asymptotic formulae for some arithmetic functions in number theory</a>, Ph.D. thesis, Loughborough University, 1998.

%e 1 is a term since the two numbers between 1^2 = 1 and (1+1)^2 = 4, 2 and 3, are not biquadratefree powerful.

%e 2 is not a term since there is a biquadratefree powerful number, 8 = 2^3, between 2^2 = 4 and (2+1)^2 = 9.

%t bqfpowQ[n_] := AllTrue[FactorInteger[n][[;; , 2]], MemberQ[{2, 3}, #] &]; Select[Range[100], !AnyTrue[Range[#^2 + 1, (# + 1)^2 - 1], bqfpowQ] &]

%Y Cf. A336175, A338325, A338326, A338327, A338388, A338389, A338390, A338391, A338392.

%K nonn

%O 1,2

%A _Amiram Eldar_, Oct 23 2020

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Last modified March 29 09:32 EDT 2024. Contains 371268 sequences. (Running on oeis4.)