I took the index of your words, converted the number to binary, additional three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to convert it to binary, additional three zeros towards the eight digits with the binary and obtained 00000010011 which translates to 19 in decimal. https://bookmarkja.com/story20882931/the-ultimate-guide-to-bip39-seed-phrase-github