Strange. In the article A138563 is described as a sequence of prime numbers that contain the substring 667. But these are obviously not prime numbers. Having a look at https://oeis.org/A138563 reveals that these are simply any numbers containing the substring.

https://oeis.org/A321001 is what they wanted, obviously easy to get them confused.

Well, they do mention they are looking up whether it exists during the interview, so it's a forgivable mistake.