I took the index of the words, converted the selection to binary, additional a few zeros, calculated the sha256 digest, took the initial part of the hexadecimal to convert it to binary, included three zeros into the 8 digits on the binary and got 00000010011 which translates to 19 in https://meshbookmarks.com/story19084364/the-fact-about-valid-bip39-seed-phrase-that-no-one-is-suggesting