I took the index on the words, converted the number to binary, additional three zeros, calculated the sha256 digest, took the main Component of the hexadecimal to transform it to binary, added three zeros to your 8 digits in the binary and received 00000010011 which translates to 19 in decimal. https://bookmarktiger.com/story18792136/5-simple-techniques-for-bip39-word-list-pdf