I took the index of your words, converted the selection to binary, included three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, included 3 zeros into the eight digits with the binary and got 00000010011 which translates to 19 in https://bookmarkpath.com/story18768440/the-definitive-guide-to-bip39-seed-phrase