I took the index with the words, transformed the number to binary, additional three zeros, calculated the sha256 digest, took the 1st Portion of the hexadecimal to transform it to binary, additional a few zeros for the eight digits of the binary and received 00000010011 which interprets to 19 in https://nybookmark.com/story20405165/an-unbiased-view-of-bip39-seed-phrase-github