I took the index in the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the primary Section of the hexadecimal to transform it to binary, extra a few zeros for the 8 digits from the binary and got 00000010011 which translates to 19 in https://webookmarks.com/story4370469/invalid-bip39-phrase-things-to-know-before-you-buy