My question is whether, using the method and specifications that I'll describe, it's possible to write Python code to apply the given filters and perform the search?

400000000000000000  to  7FFFFFFFFFFFFFFFFF
(corresponding to decimal values from 1180591620717411303424 to 2361183241434822606847).

Total number of keys in this range is:
1180591620717411303424

Filtering Criteria:
We filter out all keys whose first four hexadecimal characters (prefixes) follow the pattern:

The first character is one of 4, 5, 6, or 7,

Followed by three identical hexadecimal digits (0-9, A-F).

Thus, for each leading digit, the filtered prefixes are:

For 4:
4AAA, 4BBB, 4CCC, 4DDD, 4EEE, 4FFF, 4000, 4111, 4222, 4333, 4444, 4555, 4666, 4777, 4888, 4999

For 5:
5AAA, 5BBB, 5CCC, 5DDD, 5EEE, 5FFF, 5000, 5111, 5222, 5333, 5444, 5555, 5666, 5777, 5888, 5999

For 6:
6AAA, 6BBB, 6CCC, 6DDD, 6EEE, 6FFF, 6000, 6111, 6222, 6333, 6444, 6555, 6666, 6777, 6888, 6999

For 7:
7AAA, 7BBB, 7CCC, 7DDD, 7EEE, 7FFF, 7000, 7111, 7222, 7333, 7444, 7555, 7666, 7777, 7888, 7999

(Each group includes 16 prefixes corresponding to all possible repeated digits 0-9 and A-F.)

Calculations:
Number of filtered prefixes:
4 (leading digits) × 16 (repeated-digit prefixes) = 64

Number of keys per prefix:
Total keys ÷ 2^16 =
1180591620717411303424 ÷ 65536 = 18015511019655507

Total keys filtered:
64 × 18015511019655507 = 1152976705257952448

Percentage of keys filtered:
(1152976705257952448 ÷ 1180591620717411303424) × 100 ≈ 97.7%

Conclusion:
Applying this filtering criterion removes approximately 97.7% of all private keys within the specified range.