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Old 2018-05-09, 12:37   #5
garambois
 
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Oct 2011

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Quote:
Originally Posted by Dubslow View Post

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
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