content:mathematics:aliquot_sequences
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Aliquot sequences
Aliquot sequences are defined thus :
The aliquot sequence starting with a positive integer k can be defined formally in terms of the sum-of-divisors function ฯ1 or the aliquot sum function s in the following way:
s0 = k
sn = s(snโ1) = ฯ1(snโ1) โ snโ1 if snโ1 > 0
sn = 0 if snโ1 = 0
(if we add this condition, then the terms after 0 are all 0, and all aliquot sequences would be infinite sequence, and we can conjecture that all aliquot sequences are convergent, the limit of these sequences are usually 0 or 6) and s(0) is undefined.
Source : Wikipedia
It's conjectured - but not yet proved - that all aliquot sequences will eventually terminate.
All sequences so far tested do terminate - but it nevertheless remains unknown if all examples will.
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