I took the index from the words, converted the quantity to binary, included three zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to transform it to binary, additional three zeros to your 8 digits from the binary and got 00000010011 which interprets to 19 in decimal. https://socialwoot.com/story20460314/an-unbiased-view-of-bip39-seed-phrase-github