I took the index with the words, transformed the quantity to binary, included 3 zeros, calculated the sha256 digest, took the first part of the hexadecimal to convert it to binary, additional 3 zeros towards the 8 digits on the binary and acquired 00000010011 which translates to 19 in decimal. https://iwanttobookmark.com/story19588051/invalid-bip39-phrase-things-to-know-before-you-buy