I took the index of your words, converted the number to binary, extra 3 zeros, calculated the sha256 digest, took the 1st Portion of the hexadecimal to convert it to binary, additional three zeros towards the 8 digits of the binary and got 00000010011 which interprets to 19 in decimal. http://andersonsaeu988.iamarrows.com/from-mnemonics-to-safety-and-security-recognizing-bip39-passphrases-and-their-significance-in-copyright