Owlet puzzle #63
Released Sunday, September 6, 2026 UTC
1597
the answer for puzzle #63
The five clues
- A four-digit number between 1500 and 1600, digit sum 22.
- A prime Fibonacci number.
- A Fibonacci number whose index is also prime.
- F₁₇ — the seventeenth Fibonacci number.
- A prime Fibonacci number — divides F₃₄ since 17 divides 34.
Backstory
1597 is the 17th Fibonacci number and prime. Since 17 is also prime, this fits the pattern that F(p) is often (but not always) prime for prime p. Cassini's identity gives F(n)² − F(n−1)F(n+1) = ±1, alternating in sign.
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