I took the index in the words, converted the selection to binary, extra three zeros, calculated the sha256 digest, took the very first Element of the hexadecimal to convert it to binary, additional three zeros to your eight digits of the binary and obtained 00000010011 which translates to 19 in https://webnowmedia.com/story4421283/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator