I took the index of your words, converted the variety to binary, added 3 zeros, calculated the sha256 digest, took the first Section of the hexadecimal to transform it to binary, additional 3 zeros towards the eight digits with the binary and received 00000010011 which interprets to 19 in decimal. https://bookmarkilo.com/story19486401/not-known-factual-statements-about-bip39-explained