I took the index on the words, converted the range to binary, extra three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to transform it to binary, extra three zeros to the 8 digits with the binary and obtained 00000010011 which translates to 19 in decimal. https://get-social-now.com/story4178276/5-essential-elements-for-bip39-explained