I took the index with the words, converted the range to binary, included three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, extra a few zeros on the 8 digits of your binary and bought 00000010011 which translates to 19 https://gatherbookmarks.com/story19775669/an-unbiased-view-of-bip39-seed-phrase-github