I took the index of your words, converted the range to binary, included 3 zeros, calculated the sha256 digest, took the very first Portion of the hexadecimal to transform it to binary, additional 3 zeros to the 8 digits on the binary and bought 00000010011 which translates to 19 in https://admiralbookmarks.com/story18874939/the-fact-about-valid-bip39-seed-phrase-that-no-one-is-suggesting