I took the index with the words, transformed the range to binary, added 3 zeros, calculated the sha256 digest, took the very first Element of the hexadecimal to convert it to binary, extra 3 zeros into the eight digits of your binary and received 00000010011 which translates to 19 in https://hyperbookmarks.com/story18810825/facts-about-bip39-seed-phrase-word-list-revealed