I read a wikipedia article of a person who was very intelligent but also suffered from a mental illness. He told people around him that his next novel will be

I read a wikipedia article of a person who was very intelligent but also suffered from a mental illness. He told people around him that his next novel will be of exactly N number of words and it will end with the sentence P. I don't remember article. I read it a decade ago. It's like he was doing diffusion in his mind, subconsciously perhaps