I took the index with the words, converted the number to binary, added 3 zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to transform it to binary, included 3 zeros into the eight digits of your binary and received 00000010011 which interprets to 19 in decimal. https://exactlybookmarks.com/story19560843/little-known-facts-about-bip39-words