I took the index in the words, transformed the selection to binary, additional three zeros, calculated the sha256 digest, took the first A part of the hexadecimal to transform it to binary, extra three zeros to the eight digits from the binary and obtained 00000010011 which translates to 19 in https://bookmarkspecial.com/story19071242/an-unbiased-view-of-bip39-seed-phrase-github