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A061283
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Smallest number with exactly 2n-1 divisors.
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16
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1, 4, 16, 64, 36, 1024, 4096, 144, 65536, 262144, 576, 4194304, 1296, 900, 268435456, 1073741824, 9216, 5184, 68719476736, 36864, 1099511627776, 4398046511104, 3600, 70368744177664, 46656, 589824, 4503599627370496, 82944
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The terms are always squares.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000 (using A005179)
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FORMULA
| a(n)=Min{k | A000005(k)=2n-1}
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EXAMPLE
| If n is a prime p, then a(p)=2^(p-1); for n=15, a(n)=144 with 15 divisors: {1,2,3,4,6,8,9,12...}.
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CROSSREFS
| Cf. A016017, A000005, A000290, A005408, A005179, A003680, A037992, A016013, A016017, A055079, A048691.
Sequence in context: A135450 A162547 A073533 * A001264 A114399 A029993
Adjacent sequences: A061280 A061281 A061282 * A061284 A061285 A061286
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 22 2001
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