I took the index of your words, converted the range to binary, additional three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to convert it to binary, included 3 zeros to the eight digits in the binary and bought 00000010011 which interprets to 19 in decimal. https://bookmark-nation.com/story18868941/5-simple-techniques-for-bip39-word-list-pdf