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s4.3.4

Sum of the Squares of Arbitrary Fibonacci Sequence

1,000 questions

To find the sum of the squares of the first nn terms of an Arbitrary Fibonacci Sequence (A12+A22++An2A_1^2 + A_2^2 + \dots + A_n^2), the formula is:

Sum of Squares = An×An+1A1(A2A1)A_n \times A_{n+1} - A_1(A_2 - A_1)

For the Standard Fibonacci Sequence, where A1=1A_1=1 and A2=1A_2=1, the formula simplifies to Fn×Fn+1F_n \times F_{n+1} because the second term becomes zero.

For example, 12+12+22++3421^2 + 1^2 + 2^2 + \dots + 34^2 (the first 9 terms of the standard sequence) is F9×F10=34×55=1870F_9 \times F_{10} = 34 \times 55 = 1870.

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