Brainsteem Mathematics Challenges: Factorial Sum
Find all solutions to the equation
2n = a! + b! + c!
in positive integers a, b, c and n. Show your proof.
(Here, ! means "factorial" and, if the superscript does not show properly, the left-hand side is 2^n.)
Originally from IrMO 2001 Paper 1 Q1.
The first correct answer and further interesting comments will be rewarded with an upvote.
Enjoy!
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Thanks for the @steemstem upvote - unexpected surprise!
:-)
Hahahahahahaha.
Laughing at myself, I should just keep calm and learn from the right answer.
This is back to school for me.