I took the index on the words, transformed the selection to binary, added 3 zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, additional three zeros towards the 8 digits in the binary and received 00000010011 which translates to 19 in decimal. https://ztndz.com/story21845168/the-ultimate-guide-to-bip39-seed-phrase-github