I took the index with the words, transformed the range to binary, extra a few zeros, calculated the sha256 digest, took the initial Component of the hexadecimal to convert it to binary, additional three zeros for the 8 digits in the binary and bought 00000010011 which interprets to 19 in https://isocialfans.com/story4291818/considerations-to-know-about-bip39-word-list-pdf