I took the index in the words, transformed the quantity to binary, added a few zeros, calculated the sha256 digest, took the initial A part of the hexadecimal to convert it to binary, additional three zeros to your 8 digits of the binary and acquired 00000010011 which interprets to 19 https://squareblogs.net/edelinepge/h1-b-recognizing-bip39-a-comprehensive-overview-to-mnemonic-expressions-and