Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What number in series was the episode written by Eric Gilliland?

### Inputs:
table_name: table, columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']

### Response:
SELECT MAX No. in series FROM table WHERE Written by = Eric Gilliland