I took the index from the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to transform it to binary, additional a few zeros towards the 8 digits on the binary and got 00000010011 which translates to 19 in https://bookmarkspiral.com/story19629883/bip39-phrase-generator-can-be-fun-for-anyone