I took the index with the words, transformed the range to binary, included three zeros, calculated the sha256 digest, took the main Section of the hexadecimal to transform it to binary, extra 3 zeros on the eight digits of your binary and bought 00000010011 which interprets to 19 in decimal. https://bookmarkmiracle.com/story21294965/the-definitive-guide-to-bip39-seed-phrase