How to download FASTA sequences from NCBI using the terminal?
Alternatively, you can use the NCBI Entrez Direct UNIX E-utilities

Basically, you have to download the install file here: https://www.ncbi.nlm.nih.gov/books/NBK179288/bin/install-edirect.sh

In the terminal, install it using: source ./install-edirect.sh

Then, you can download your sequence by doing:

esearch -db nucleotide -query "NC_030850.1" | efetch -format fasta &gt; NC_030850.1.fasta

And you should find your fasta sequence downloaded. 

As you have several sequences to download, I think it will be quite easy to add this command into a little bash script to process all of them.

More readings about that: http://bioinformatics.cvr.ac.uk/blog/ncbi-entrez-direct-unix-e-utilities/ and https://www.ncbi.nlm.nih.gov/books/NBK179288/