I took the index in the words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the main Element of the hexadecimal to transform it to binary, additional a few zeros to the 8 digits on the binary and received 00000010011 which translates to 19 in https://bookmarkcork.com/story19383148/the-5-second-trick-for-ledger-seed-phrase-bip39