I took the index in the words, converted the selection to binary, included three zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to convert it to binary, extra 3 zeros to your 8 digits with the binary and bought 00000010011 which translates to 19 in decimal. https://hubwebsites.com/story20122894/an-unbiased-view-of-bip39-seed-phrase-github