Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
From the description "There will always be only one integer that appears an odd number of times."
Your sequence does not fulfil this promise. Integers 5 and 11 both appear an odd number of times (3 and 1 respectively).
Nice :)