I took the index in the words, transformed the selection to binary, added three zeros, calculated the sha256 digest, took the very first Portion of the hexadecimal to convert it to binary, added three zeros on the 8 digits with the binary and got 00000010011 which interprets to 19 in https://webnowmedia.com/story4297970/bip39-seed-phrase-mnemonics-generator-an-overview