SCHEMA:
CREATE TABLE table_21481509_4 (n INTEGER, r1b1c4__r_v69_ VARCHAR)
USER:
What is the largest n value for 55.6% r1b1c4 (r-v69)?

QUERY:
SELECT MAX(n) FROM table_21481509_4 WHERE r1b1c4__r_v69_ = "55.6%"