I took the index of your words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the primary part of the hexadecimal to transform it to binary, extra 3 zeros into the eight digits on the binary and got 00000010011 which translates to 19 in decimal. http://jaspermuxp089.yousher.com/from-mnemonics-to-security-comprehending-bip39-passphrases-and-their-significance-in-copyright