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
KEYWORD
nonn
AUTHOR
Michel Lagneau, Sep 02 2011
EXTENSIONS
a(11)-a(25) from Nathaniel Johnston, Sep 02 2011
STATUS
approved