I took the index in the words, transformed the quantity to binary, included three zeros, calculated the sha256 digest, took the 1st Section of the hexadecimal to convert it to binary, additional a few zeros on the 8 digits of your binary and received 00000010011 which interprets to 19 in https://throbsocial.com/story20715950/bip39-seed-phrase-mnemonics-generator-an-overview