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A194771 Even numbers that divide the sum of their even divisors. 1
2, 12, 56, 240, 992, 1344, 16256, 60480, 65520, 1047552, 4357080, 47139840, 67100672, 91065600, 285981696, 919636480, 2758909440, 2952609792, 17179738112, 28364878080, 63996791040, 87722956800, 102002360320, 132867440640, 137438691328 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Since the sum of even divisors of an odd number is zero, every odd number divides its sum of even divisors. - Nathaniel Johnston, Sep 02 2011

LINKS

Table of n, a(n) for n=1..25.

FORMULA

a(n) = 2*A007691(n).

EXAMPLE

The divisors of 56 are { 1, 2, 4, 7, 8, 14, 28, 56 } and the sum of the even divisors is 2 + 4 + 8 + 14 + 28 + 56 = 112, hence 56 divides 112, so 56 is in the sequence.

MAPLE

with(numtheory):for n from 1 to 10000000 do if(sigma(n) mod n = 0)then print(2*n):fi:od:

CROSSREFS

Cf. A146076.

Sequence in context: A285146 A127216 A006659 * A127221 A020522 A037130

Adjacent sequences:  A194768 A194769 A194770 * A194772 A194773 A194774

KEYWORD

nonn

AUTHOR

Michel Lagneau, Sep 02 2011

EXTENSIONS

a(11) - a(25) from Nathaniel Johnston, Sep 02 2011

STATUS

approved

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Last modified October 18 08:08 EDT 2019. Contains 328146 sequences. (Running on oeis4.)