I took the index with the words, transformed the range to binary, added 3 zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to transform it to binary, included three zeros on the 8 digits of your binary and got 00000010011 which translates to 19 in decimal. https://bookmarksurl.com/story4478390/examine-this-report-on-bip39-mnemonic-phrase-tool