They're the base cases of the recursion and are therefore 0 and 1 by definition. You need two base cases because the recursive function uses the previous two numbers in the series to calculate the current one.
Edit: Sorry calling them base cases is inaccurate since that's another thing entirely in recursion. The reason they're defined stands though, the recurrence requires two initial values to work.
RevolutionaryRough37 t1_j5r5ybb wrote
Reply to comment by RecalcitrantHuman in My friend claims that understanding a Fibonacci sequence is hard, but I disagree. by porichoygupto
They're the base cases of the recursion and are therefore 0 and 1 by definition. You need two base cases because the recursive function uses the previous two numbers in the series to calculate the current one.
Edit: Sorry calling them base cases is inaccurate since that's another thing entirely in recursion. The reason they're defined stands though, the recurrence requires two initial values to work.