I took the index of your words, transformed the selection to binary, included a few zeros, calculated the sha256 digest, took the first A part of the hexadecimal to convert it to binary, additional three zeros towards the 8 digits of the binary and received 00000010011 which translates to 19 https://getsocialnetwork.com/story4391272/a-secret-weapon-for-bip39-words-to-numbers