I took the index of the words, transformed the selection to binary, included three zeros, calculated the sha256 digest, took the primary Portion of the hexadecimal to convert it to binary, included three zeros for the eight digits of your binary and got 00000010011 which translates to 19 in decimal. https://pr6bookmark.com/story18959800/the-definitive-guide-to-bip39-seed-phrase