How this calculation works
Find an exact term of the Pell sequence.
THE FORMULA
P₀=0, P₁=1, Pₙ=2Pₙ₋₁+Pₙ₋₂A worked example
The sequence begins 0, 1, 2, 5, 12, 29, 70.
Good to know
The initial zero is at index zero.
Reference: NIST DLMF, Functions of Number Theory (opens in a new tab) ↗
Read the result
Find an exact term of the Pell sequence.
The primary result is labeled “Pell number”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
The initial zero is at index zero.
For a related exercise, try the greatest common divisor.
A few questions, answered
How can I check the default inputs by hand?
The sequence begins 0, 1, 2, 5, 12, 29, 70.
Which rule does this calculator apply?
P₀=0, P₁=1, Pₙ=2Pₙ₋₁+Pₙ₋₂