Four is Magic is a popular math game. You spell out any number into English:
i.e. = one hundred seventeen
And then you add the total letters together. So 'one hundred seventeen' has letters.
When we continue this:
i.e.
It is notable that "four" has exactly letters in it. It is the only number with this quality.
I came up with a bonus feature to this puzzle.
Instead of adding the words count of each word like this:
i.e. = one hundred seventeen =
We will be taking the product of each word count:
i.e. = one hundred seventeen =
This leads to very different results! is still special, but now are there other numbers with this quality?
Yes, there are!
Can you find the others?
If you can find solutions for , be sure to post them in this sequence: A058230.
How can you code this problem?
What are the solutions to both problems?
My 9th solution is a monstrous 42 digit number!
Are there more than 9 solutions?
What other interesting numbers can you find?
Turns out these numbers are called Fortuitous Numbers.
Easy Math Editor
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Comments
Fascinating! I just might try coding this. I'll probably even use this digit-separating formula I came up with a while back.
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Thank you! It's a really interesting programming challenge. That's also a very useful formula!
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Phew! 100 lines of code later, and it takes me a minute to reach the fourth OEIS entry. :)
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Does that mean that you found more entries than are listed in the OEIS sequence, or am I reading that wrong?
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Yes, I found 3 more, the largest of which has 42 digits. I’m trying to add the new terms to OEIS, but now I am waiting for approval from an editor.
I’m also adding a new sequence focused on numbers of type “a -> b -> ... -> a”. But that one also needs to be approved by an editor.
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Woah, cool! How long did that take?
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But then no new solutions appeared after 24 hours of running, up to about ~ 10^130
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