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1, 2, 3, 8, 5, 36, 7, 32, 27, 100, 11, 144, 13, 196, 225, 128, 17, 324, 19, 400, 441, 484, 23, 576, 125, 676, 243, 784, 29, 900, 31, 512, 1089, 1156, 1225, 1296, 37, 1444, 1521, 1600, 41, 1764, 43, 1936, 2025, 2116, 47, 2304, 343, 2500, 2601, 2704, 53, 2916, 3025, 3136, 3249, 3364, 59, 3600
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| For n>1, a(n) = n iff n is prime.
a(n) is n times the least common multiple of the proper divisors of n, a(n) = n*A048671(n). [Peter Luschny, Jun 22 2011]
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FORMULA
| A140579^(-1) * (1, 4, 9, 16, 25,...).
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EXAMPLE
| A140579 = an infinite lower triangular matrix with A014963 in the main diagonal and the rest zeros; where A014963 = (1, 2, 3, 2, 5, 1, 7,...).
a(5) = 5 = 1/A014963(5) * 25 = (1/5)*25.
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MAPLE
| A140651 := n -> n*ilcm(op(numtheory[divisors](n) minus {1, n})); seq(A140651(i), i=1..60); # Peter Luschny, Jun 22 2011
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CROSSREFS
| Cf. A140579, A014963.
Sequence in context: A119794 A117987 A091136 * A190997 A184392 A007955
Adjacent sequences: A140648 A140649 A140650 * A140652 A140653 A140654
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KEYWORD
| nonn
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AUTHOR
| Gary W. Adamson and Mats Granvik (qntmpkt(AT)yahoo.com), May 20 2008
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EXTENSIONS
| a(15) - a(60) from Peter Luschny, Jun 22 2011.
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