The original pattern uses prime check (as per this code). OP claimed an exact match with http://oeis.org/A054521 http://oeis.org/A054521 - but this isn't true

The original pattern uses prime check (as per this code). OP claimed an exact match with http://oeis.org/A054521 http://oeis.org/A054521 - but this isn't true for many N (see vietjtnguyen's streamable). Perhaps it approaches it as N grows large?