I took the index in the words, transformed the range to binary, additional three zeros, calculated the sha256 digest, took the main A part of the hexadecimal to transform it to binary, extra 3 zeros to your eight digits on the binary and obtained 00000010011 which translates to 19 in https://bookmark-rss.com/story18720871/an-unbiased-view-of-bip39-seed-phrase-github