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Search: id:A145899
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| A145899 |
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Each element n of the sequence has more solutions m to sigma(m)=n than does any positive integer less than n. |
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| 1, 12, 24, 72, 168, 240, 336, 360, 504, 576, 720, 1440, 2880, 4320, 5760, 8640, 10080, 15120, 17280, 20160, 30240, 40320, 60480, 120960, 181440, 241920, 362880, 483840, 604800, 725760, 1088640, 1209600, 1451520, 2177280, 2419200, 2903040, 3628800
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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sigma(m)=1 has only one solution: m=1.
sigma(m)=12 has two solutions, m=6 and m=11; 12 is the smallest number with more than one such solutions.
sigma(m)=24 has three solutions, m=14,m=15 and m=23; 24 is the smallest number with more than two such solutions.
sigma(m)=72 has five solutions, m=30, m=46, m=51, m=55 and m=71; 72 is the smallest number with more than three such solutions.
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PROGRAM
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(PARI) {m=3650000; v=vectorsmall(m); for(n=1, m, s=sigma(n); if(s<=m, v[s]++)); g=0; j=1; while(j<=m, if(v[j]<=g, j++, g=v[j]; print1(j, ", ")))} [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 27 2008]
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CROSSREFS
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Cf. A000203 (sum of divisors of n), A054973 (number of numbers whose divisors sum to n), A007368 (smallest k such that sigma(x) = k has exactly n solutions). [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 27 2008]
Sequence in context: A087105 A063975 A001335 this_sequence A001041 A081751 A120360
Adjacent sequences: A145896 A145897 A145898 this_sequence A145900 A145901 A145902
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KEYWORD
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nonn
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AUTHOR
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Douglas E. Iannucci (diannuc(AT)uvi.edu), Oct 22 2008
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EXTENSIONS
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Extended beyond a(15) by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 27 2008
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