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Fibonacci Number Calculator

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This script can calculate any Fibonacci number between 1 and the 10,000+ digit behemoth F50000 at incredible speeds. In fact, Fibonacci numbers less than F10000 can be calculated with this tool in less than a second, and F50000 can be computed in under 12 seconds.

The   th Fibonacci number.

For those of you that don't know what Fibonacci numbers are, they are the sequence of numbers defined by the recurrence relation:

Fn = Fn-1 + Fn-2

and F1 and F2 are both set to 1. Thus, the first few Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, ...

As an example, here is the 1,000th Fibonacci number:

43 466 557 686 937 456 435 688 527 675 040 625 802 564 660 517 371 780 402 481 729 089 536 555 417 949 051 890 403 879 840 079 255 169 295 922 593 080 322 634 775 209 689 623 239 873 322 471 161 642 996 440 906 533 187 938 298 969 649 928 516 003 704 476 137 795 166 849 228 875