[OC] Average number of prime factors for numbers between 0 and 10 000 000

Posted by Swimming_Security_27

10 comments
  1. I’m mostly posting this because i couldn’t find a graph of this when i searched for it myself, so i thought i would put it out there.

    A function that approximates the data is 0.070 * log( 2.150 * 10^(-4) * x) + 3.322. (But i wouldn’t trust it too much)

    **The backstory:**

    I came across a sequence and messed around with it a bit. For fun i thought i would see how many prime factors the numbers in the sequence had. I was very surprised when large numbers in the sequence had seemingly few prime factors. So i thought i would check out if there was something weird going on. (spoiler: There wasn’t, I just overestimated the number of prime factors that numbers actually have. Who would have thought that (on average) a number around 10 000 000 has less than FOUR prime factors??)

    **The sequence:**

    I was tapping my fingers on the table, and was wondering how many ways i could put down all fingers on one hand. The answer is obviously 5! = 120. Or if you use both hands, the number is 10! = 3 268 800

    But what if you can’t put down two neighbouring fingers one after the other? I made a sh***y python script and found out:

    # of fingers – Possible ways to put them down

    1 – 1

    2 – 0

    3 – 0

    4 – 2

    5 – 14

    6 – 90

    7 – 646

    8 – 5 242

    9 – 47 622

    10 – 479 306

    11 – 5 296 790

    12 – 63 779 034

    13 – Ran out of memory

    Thanks for coming to my TED talk. 

  2. This is really interesting. I understand why you grouped the averages in buckets of 10k, but I’d also love to see an unaveraged plot of the number of prime factors for all nonprime numbers between 0 and 10,000,000, just to have laid my eyes on it.

  3. The fact that we can casually count the number of primes between 0 and 10,000,000 is crazy to me. A computer is a fucking incredible invention.

  4. could have made the graph a bit nicer since the data is so cool..

  5. Do we know what the limit is as x goes to infinity? Why does it look like 4ish, is it just because of the bounds of the data?

  6. Drives me crazy when people don’t use commas in the number format (ie x axis).

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