Prime Number Generation [Different Approaches]

Question

Recently posted some codes on prime number generation. Not the common approach...

Sieve of Eratosthenes (uncommon approach)
https://code.sololearn.com/cj0ipKu7uIEm/?ref=app

Sieve of Sundaram (rare and faster approach)
https://code.sololearn.com/c3p5K1MKR181/?ref=app

Check them out and post your comments.

Answer 1

https://code.sololearn.com/cqJpM34ICi9H/?ref=app

Answer 2

Check out this

https://code.sololearn.com/cuuU0HZJ50QD/?ref=app