दी गई अल्फ़ान्यूमेरिक श्रृंखला को पूरा करने के लिए लुप्त पद ज्ञात कीजिए: P3, Q5, ________, S11

Which number will replace the question mark (?) in the following series? 83, 79, 71, 67, 59, 55, ?

Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete? HLE23, JJH21, LHK19, NFN17, ?