I took the index in the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the very first Element of the hexadecimal to transform it to binary, added three zeros for the 8 digits in the binary and received 00000010011 which translates to 19 in https://bbsocialclub.com/story20724932/facts-about-bip39-seed-phrase-github-revealed