Quote:
Originally Posted by Dubslow
Originally Posted by 10metreh View Post
2σ(a)a
Is there an OEIS entry for these sequence (starting with f(0)=3) ?

And what's about odd perfect numbers, if they exist ?
Starting with f(0)=2, we have : 2, 4, 10, 26, 58, 122, 250, 686 ...
There is no OEIS entry for this sequence.
Just for fun, I calculated the first 348 terms of this sequence. Curiously, we do not find the prime number 3 in the decomposition into prime numbers of these terms.
You can see here :
http://www.aliquotes.com/parfait_2_z.txt