I took the index on the words, converted the range to binary, added three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to convert it to binary, additional 3 zeros for the 8 digits with the binary and got 00000010011 which translates to 19 in decimal. https://wavesocialmedia.com/story4450645/considerations-to-know-about-bip39-word-list-pdf