I took the index of the words, converted the variety to binary, included three zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to convert it to binary, extra three zeros to your 8 digits of the binary and received 00000010011 which translates to 19 in decimal. https://bookmarkmoz.com/story19637052/facts-about-bip39-seed-phrase-github-revealed