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A061111
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a(1) = 1; a(n) = smallest number such that the concatenation a(1).0^*.a(2).0^*....0^*.a(n) is a perfect cube (where any number of 0's can be inserted between the terms).
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1
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OFFSET
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1,2
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COMMENTS
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The implication is that 10...01, 10...02, 10...03, ..., 10...024 are never cubes for any number of internal zeros, while 125 IS a cube, so a(2) = 25. - N. J. A. Sloane, Jul 21 2001
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LINKS
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EXAMPLE
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a(1) = 1, a(1).a(2) = 125 = 5^3, a(1).a(2).a(3) = 1259712 = 108^3, a(1).a(2).a(3).a(4) = 232679^3.
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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Offset and a(4) corrected and more terms from Sean A. Irvine, Jan 21 2023
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STATUS
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approved
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