I took the index in the words, converted the variety to binary, included 3 zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to convert it to binary, included three zeros into the 8 digits of your binary and received 00000010011 which translates to 19 in decimal. https://bookmarkproduct.com/story19566618/little-known-facts-about-bip39-seed-phrase-list