I took the index on the words, transformed the range to binary, additional three zeros, calculated the sha256 digest, took the main A part of the hexadecimal to convert it to binary, additional a few zeros to your eight digits on the binary and received 00000010011 which interprets to 19 https://thebookmarklist.com/story18934633/not-known-factual-statements-about-bip39-explained