I took the index of your words, converted the range to binary, added three zeros, calculated the sha256 digest, took the primary Portion of the hexadecimal to transform it to binary, added 3 zeros to the eight digits on the binary and acquired 00000010011 which interprets to 19 in decimal. https://my-social-box.com/story4892188/the-definitive-guide-to-bip39-seed-phrase