I took the index in the words, transformed the number to binary, additional 3 zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to convert it to binary, additional 3 zeros to your 8 digits in the binary and received 00000010011 which interprets to 19 in decimal. https://livebookmarking.com/story18786852/the-invalid-bip39-phrase-diaries