I took the index with the words, transformed the selection to binary, added 3 zeros, calculated the sha256 digest, took the main part of the hexadecimal to transform it to binary, included three zeros towards the 8 digits from the binary and got 00000010011 which interprets to 19 in decimal. https://top10bookmark.com/story18826480/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator