I took the index with the words, transformed the selection to binary, extra a few zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to convert it to binary, extra 3 zeros towards the eight digits on the binary and obtained 00000010011 which interprets to 19 in https://socialtechnet.com/story4622774/new-step-by-step-map-for-ledger-seed-phrase-bip39