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Search: id:A046987
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| A046987 |
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Multiply perfect numbers whose average divisor is (a) not an integer and (b) does not divide the number itself. |
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+0
5
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| 120, 523776, 1476304896, 31998395520, 30823866178560, 69357059049509038080, 4010059765937523916800, 27099073228001299660800, 686498980761986918441287680, 2827987212986831882236723200
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a=s1/s0, b=x/a, c=s1/x, where s1 is the sum and s0 is the number of divisors of x. Here only c is an integer, while a and b are not.
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EXAMPLE
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x=523776,number of divisors is 80, Sigma[ 1,523776 ]=1571328 and the relevant quotients are: a=19641.6, b=26.667, c=3(integer).
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CROSSREFS
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In A007691 but not in A003601 or A001599. Cf. A046985, A046986.
Sequence in context: A158043 A009767 A003789 this_sequence A127232 A166351 A147964
Adjacent sequences: A046984 A046985 A046986 this_sequence A046988 A046989 A046990
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu)
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EXTENSIONS
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a(5)-a(10) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 30 2008
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