Let us define a sequence S(N): a1= N,
a_n= sum of all factors of a_n-1, excluding a_n-1 itself. Most sequences either converge or begin to repeat.

S(12) → 12,16,15,9,4,3,1,1,1...
S(6) → 6,6,6,6,...
S(220) → 220,284,220,284,220,284,...
Try to evaluate S(50), S(80), S(99).

How about S(138)?
WILL IT CONVERGE TO 1,1,1,...?
Please comment!

(In reply to re: computer solution by Jer)

btw 276 is twice 138

Posted by Ady TZIDON on 2018-05-12 10:44:47