Definition:Factorion
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Definition
A factorion (base $b$) is a positive integer which, when expressed in base $b$, equals the sum of the factorials of its digits.
When the number base is not given, base $10$ is assumed.
Examples
Factorions Base $10$
The following positive integers are the only factorions base $10$:
- $1, 2, 145, 40 \, 585$
Sources
- Weisstein, Eric W. "Factorion." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Factorion.html