I took the index with the words, transformed the quantity to binary, added 3 zeros, calculated the sha256 digest, took the first Section of the hexadecimal to convert it to binary, extra 3 zeros on the 8 digits of your binary and obtained 00000010011 which translates to 19 in decimal. https://toplistar.com/story20844610/the-2-minute-rule-for-bip39-all-words