

A046987


Multiply perfect numbers whose average divisor is (a) not an integer and (b) does not divide the number itself.


7



120, 523776, 1476304896, 31998395520, 30823866178560, 69357059049509038080, 4010059765937523916800, 27099073228001299660800, 686498980761986918441287680, 2827987212986831882236723200
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..10.


FORMULA

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.


EXAMPLE

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).


CROSSREFS

In A007691 but not in A003601 or A001599. Cf. A046985, A046986.
Sequence in context: A003789 A325024 A325026 * A127232 A208191 A166351
Adjacent sequences: A046984 A046985 A046986 * A046988 A046989 A046990


KEYWORD

nonn


AUTHOR

Labos Elemer


EXTENSIONS

a(5)a(10) from Donovan Johnson, Nov 30 2008


STATUS

approved



