chore(Python): add sum of n numbers using recursion (#770)

algorithms/Python/README.md

@@ -25,6 +25,7 @@
 - [Factorial](recursion/factorial.py)
 - [n-th Fibonacci number](recursion/nth_fibonacci_number.py)
 - [Recursive Insertion Sort](recursion/recursive_insertion_sort.py)
+- [Recursive Sum of n numbers](recursion/recursive-sum-of-n-numbers.py)
 
 ## Scheduling
 - [Interval Scheduling](scheduling/interval_scheduling.py)

recursive-sum-of-n-numbers.py

@@ -0,0 +1,12 @@
+def recsum(n):
+    if n<=1:
+        return(n)
+    else:
+        return(n+recsum(n-1))
+
+n= 15
+
+if n<0:
+    print("Enter a positive integer")
+else:
+    print("Sum =",recsum(n))