I took the index from the words, transformed the quantity to binary, included three zeros, calculated the sha256 digest, took the primary Element of the hexadecimal to convert it to binary, additional three zeros to your eight digits of your binary and got 00000010011 which interprets to 19 in decimal. https://bookmarkssocial.com/story18788731/bip39-seed-phrase-mnemonics-generator-an-overview