- Fibonacci family
The Fibonacci family includes all sequences of the form:
i.e., the sequences defined by a second-order linear homogeneous
recurrence relation .Special cases
Fibonacci sequence
A special and the most known case is the Fibonacci sequence, where "X" = 0, "Y" = 1, and "A" = "B" = 1.
Square root of 2
Set "A" to 1, and "B" to 2, and start with 1,3 and 1,2. This gives two sequences.
*1, 3, 7, 17, 41, 99, 239... OEIS|id=A001333
*1, 2, 5, 12, 29, 70, 169... Pell numbers, OEIS|id=A000129Taking quotients of corresponding elements we get:
:
Solving the recurrence relations shows that this sequence has limit .
See also
*
Lucas sequence
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