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

Author

Michel Lagneau, Sep 02 2011

Keywords

• nonn

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

Examples

			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.
		

Crossrefs

Cf. A146076.

Programs

Maple

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

Formula

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

Extensions

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