I took the index in the words, transformed the selection to binary, additional three zeros, calculated the sha256 digest, took the initial Element of the hexadecimal to convert it to binary, extra 3 zeros towards the eight digits of your binary and got 00000010011 which translates to 19 in decimal. https://dailybookmarkhit.com/story18864922/bip39-seed-phrase-fundamentals-explained