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A194771
Even numbers that divide the sum of their even divisors.
3
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
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
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
KEYWORD
nonn
AUTHOR
Michel Lagneau, Sep 02 2011
EXTENSIONS
a(11)-a(25) from Nathaniel Johnston, Sep 02 2011
STATUS
approved