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A046987 Multiply perfect numbers whose average divisor is (a) not an integer and (b) does not divide the number itself. 5
120, 523776, 1476304896, 31998395520, 30823866178560, 69357059049509038080, 4010059765937523916800, 27099073228001299660800, 686498980761986918441287680, 2827987212986831882236723200 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 25 16:14 EDT 2019. Contains 326324 sequences. (Running on oeis4.)