I took the index in the words, transformed the range to binary, added 3 zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to convert it to binary, additional a few zeros to your 8 digits on the binary and bought 00000010011 which translates to 19 in https://funny-lists.com/story19974743/the-greatest-guide-to-seed-phrase-bip39