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A165315
a(1)=2. If s is the largest integer such that n = r^s, r = positive integer, then a(n) = the smallest integer > a(n-1) such that a(n) = t^s, t = positive integer.
1
2, 3, 4, 9, 10, 11, 12, 27, 36, 37, 38, 39, 40, 41, 42, 81, 82, 83, 84, 85, 86, 87, 88, 89, 100, 101, 125, 126, 127, 128, 129, 243, 244, 245, 246, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298
OFFSET
1,1
COMMENTS
The variable s need not necessarily be the largest integer such that a(n) = t^s, t = some positive integer. (For example, a(3) = 4 because 4 is a first power, like 3.)
If a(1) had equaled 1 instead, then the sequence would have been just the sequence of positive integers, obviously.
LINKS
EXAMPLE
a(9) = 36 because 9 = 3^2, and because 36 is the smallest square > a(8) = 27.
MATHEMATICA
FoldList[Ceiling[(#1 + 1)^(1/(s = GCD @@ FactorInteger[#2][[All, 2]]))]^s &, 2, Range[2, 58]] (* Ivan Neretin, Apr 26 2017 *)
CROSSREFS
Sequence in context: A047454 A373788 A081870 * A284681 A309346 A047339
KEYWORD
nonn
AUTHOR
Leroy Quet, Sep 14 2009
EXTENSIONS
Edited by Ray Chandler, Mar 14 2010
STATUS
approved