I took the index of your words, transformed the range to binary, included a few zeros, calculated the sha256 digest, took the first part of the hexadecimal to convert it to binary, added 3 zeros for the 8 digits with the binary and received 00000010011 which interprets to 19 in https://monobookmarks.com/story18716436/detailed-notes-on-copyright-wallet-seed-phrase-out-of-bip39