OFFSET
1,1
COMMENTS
Positions of 3's in A338326.
The asymptotic density of this sequence is 0.008234579... (Dehkordi, 1998).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..6500
Massoud H. Dehkordi, Asymptotic formulae for some arithmetic functions in number theory, Ph.D. thesis, Loughborough University, 1998.
EXAMPLE
36 is a term since there are exactly three biquadratefree powerful numbers, 1323 = 3^3 * 7^2, 1331 = 11^3 and 1352 = 2^3 * 13^2, between 36^2 = 1296 and (36+1)^2 = 1369.
MATHEMATICA
bqfpowQ[n_] := AllTrue[FactorInteger[n][[;; , 2]], MemberQ[{2, 3}, #] &]; Select[Range[1000], Count[Range[#^2 + 1, (# + 1)^2 - 1], _?bqfpowQ] == 3 &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 23 2020
STATUS
approved