I took the index with the words, converted the selection to binary, included three zeros, calculated the sha256 digest, took the primary Element of the hexadecimal to convert it to binary, included 3 zeros towards the 8 digits of the binary and obtained 00000010011 which translates to 19 in decimal. https://web.archive.org/web/20241213201435/https://bip39-phrase.com/