add Ramanujan sum

Author: daedalus

ramanujan_sum.py

@@ -0,0 +1,16 @@
+# Author Dario Clavijo 2023
+# based on https://en.wikipedia.org/wiki/Ramanujan%27s_sum
+
+from gmpy2 import *
+
+ipi2 = (2j) * complex(gmpy2.const_pi())
+
+def c(q,n):
+  sum_ = 0
+  nipi2 = ipi2 * n
+  for a in range(1, q+1):
+    if gcd(a,q) == 1:
+      sum_ += exp(nipi2 * (a/q))
+  return sum_
+
+print([c(1,n).real for n in range(1, 31)])