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A046985
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Multiply perfect numbers whose average divisor is an integer and divides the number itself.
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13
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1, 6, 672, 30240, 32760, 23569920, 45532800, 14182439040, 51001180160, 153003540480, 403031236608, 13661860101120, 154345556085770649600, 9186050031556349952000, 143573364313605309726720
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OFFSET
| 1,2
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COMMENTS
| sigma_0(n) is the number of divisors of n (A000005).
sigma_1(n) is the sum of the divisors of n [same as sigma(n)] (A000203).
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FORMULA
| a=s1/s0, b=(x*s0)/s1 and c=s1/x, where s1=Sigma_1(x), s0=Sigma_0(x), the sum and number of divisors of x; a, b, c are integers.
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EXAMPLE
| x=45532800, Sigma_0=384, Sigma_1=182131200. The three quotients are as follows: a=474300, b=96 and c=4.
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CROSSREFS
| Intersection of A003601, A007691 and A001599. Cf. A046986, A046987.
Sequence in context: A206458 A132928 A055317 * A159371 A159620 A125535
Adjacent sequences: A046982 A046983 A046984 * A046986 A046987 A046988
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu)
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EXTENSIONS
| a(10)-a(15) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 30 2008
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