I took the index with the words, transformed the number to binary, additional a few zeros, calculated the sha256 digest, took the 1st Element of the hexadecimal to transform it to binary, included 3 zeros towards the 8 digits in the binary and acquired 00000010011 which translates to 19 in https://followbookmarks.com/story19569104/the-definitive-guide-to-bip39-seed-phrase