A194771 Even numbers that divide the sum of their even divisors.

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

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