Why not extend the sequence back as far as you can:"At Phaethon's Reach, Follow the Path of Souls, DB-IB Fi(0) T-1319 SUM(10,7,5,3)"
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Could Fi(0) mean the start of the Fibonacci series?
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http://i.imgur.com/jX9uGYK.png
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If we take the numbers 1319, 1984, 3303 as Fibonacci series, we can extend these as follows, 654,665,1319,1984,3303.
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If we join numbers 654,665,1319 as follows, 6546651319 we have ten numbers, from this result, we then select numbers according to positions indicated by the numbers 10,7,5,3.
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We then obtain for position 10 we get a 9, for position 7 we get a 1, for position 5 we get a 6 and for position 3 we get a 4. From this we obtain numbers 9164.
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Therefore, either the number 9164 represents something as is, OR, we could SUM(9+1+6+4) = 20, which is the Fibonacci position F(20) which equals 6765.
643, 11, 654, 665, 1319, 1984, 3303
Any more than that and negative numbers would feature, so perhaps continue your method from here:
10th number: 6
7th number: 5
5th number: 1
3rd number: 3
SUM (6,5,1,3) is 15, or F(15)=610
I've no idea how to translate this into a location, though