SCHEMA:
CREATE TABLE table_17257687_1 (episode_number VARCHAR, event_4 VARCHAR, event_1 VARCHAR)
USER:
On which episode number is event 4 The Wall and event 1 the Pendulum?

QUERY:
SELECT COUNT(episode_number) FROM table_17257687_1 WHERE event_4 = "The Wall" AND event_1 = "Pendulum"