I took the index on the words, transformed the amount to binary, extra three zeros, calculated the sha256 digest, took the main part of the hexadecimal to convert it to binary, additional a few zeros on the 8 digits on the binary and got 00000010011 which translates to 19 in https://bookmarkshut.com/story19753131/the-greatest-guide-to-seed-phrase-bip39