Erster Commit

A10/sum_of_arith_sequence/main.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+
+// Sum of Arithmetic Sequence
+// an = a1 + (n-1) * d
+// Sn = (a1 + an) * n/2
+
+int main(void) {
+
+    int d, a1, n, an, Sn;
+
+    printf("Sum of Arithmetic Sequence!\n");
+
+    printf("a1:");
+    scanf("%d", &a1);
+
+    printf("d:");
+    scanf("%d", &d);
+
+    printf("n:");
+    scanf("%d", &n);
+
+
+    //an = a1 + (n-1) * d;
+    //Sn = (a1 + an) * n/2;
+
+    Sn = (a1 + (a1+(n-1)*d) ) * n/2;
+
+    printf("Sn := %d\n", Sn);
+
+
+    return 0;
+}