I took the index of your words, converted the quantity to binary, added 3 zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to convert it to binary, included three zeros to your eight digits on the binary and got 00000010011 which translates to 19 in decimal. https://getsocialsource.com/story4356586/facts-about-bip39-seed-phrase-github-revealed