Blockchain.info is just one of many block explorers, and it ignores transactions with low fee. There is no "one memory pool".
Your transaction does show up on
blockexplorer.com. At 20 satoshi/byte, I would have expected blockchain.info to show it though.
At this low fee, it's very unlikely to confirm. It's best to abandon the transaction and try again with a higher fee.
Thank you for the answer!
What is the best way to abandon the transaction with bitcoin core?
I've never done it before. I have googled it, but I am not sure which is the right way.