Consider the numbers , and :
and .
and .
and .
, and are the only numbers that have as sum of the prime factors (counted with multiplicity).
We define to be the sum of all numbers where the sum of the prime factors (with multiplicity) of is .
Hence .
Other examples: , , , .
The Fibonacci sequence is , , , , , ....
Find the last nine digits of .
Write-up coming later
The complete problem is available here. An approach, code, and answer will be added later.