Explanation:
The prime 43 appears in the sixth twin-prime pair 41, 43. As a sum of four or fewer squares: 43 = 32 + 32 + 52 = 12 + 12 + 42 + 52 = 32 + 32 + 32 + 42. ... As a difference of two squares: 43 = 222 − 212.
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