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A125845
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n-digit numbers having n divisors each with a different number of digits.
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2
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1, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 121, 169, 289, 361, 529, 841, 961, 1111, 1133, 1177, 1199, 1243, 1313, 1331, 1339, 1391, 1397, 1417, 1441, 1469, 1507, 1529, 1639, 1651, 1661, 1703, 1717, 1727, 1751, 1781
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A subsequence of A095862.
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LINKS
| Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Sam Vandervelde, The Mandelbrot Competition, round 2, 2006-07, asked for the smallest composite number in this list.
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EXAMPLE
| 1 is the only one-digit number with only one factor. Two-digit primes are the only two-digit numbers in the list since they have a one-digit factor (1) and a two-digit factor (themselves). Three-digit squares of two-digit primes are the only three-digit numbers in the list, since only numbers of the form p^2 can have three factors.
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CROSSREFS
| A125315 gives the smallest n-digit number of this form for each n.
Sequence in context: A140461 A120533 A095862 * A108871 A167847 A135779
Adjacent sequences: A125842 A125843 A125844 * A125846 A125847 A125848
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KEYWORD
| base,nonn
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AUTHOR
| Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), Dec 11 2006
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