I took the index with the words, converted the variety to binary, included 3 zeros, calculated the sha256 digest, took the first Section of the hexadecimal to transform it to binary, additional 3 zeros to the 8 digits of your binary and received 00000010011 which interprets to 19 in decimal. https://pr8bookmarks.com/story19112295/facts-about-bip39-seed-phrase-word-list-revealed