I took the index with the words, converted the range to binary, added 3 zeros, calculated the sha256 digest, took the first Element of the hexadecimal to transform it to binary, additional 3 zeros to your eight digits from the binary and obtained 00000010011 which translates to 19 in decimal. https://wavesocialmedia.com/story4435541/getting-my-bip39-words-to-numbers-to-work