We can easily verify that none of the entries in the first seven rows of Pascal's triangle are divisible by 7:
-
-
-
-
-
- 1
-
-
-
-
-
- 1
-
- 1
-
-
-
-
- 1
-
- 2
-
- 1
-
-
-
- 1
-
- 3
-
- 3
-
- 1
-
-
- 1
-
- 4
-
- 6
-
- 4
-
- 1
-
- 1
-
- 5
-
-10
-
-10
-
- 5
-
- 1
-1
-
- 6
-
-15
-
-20
-
-15
-
- 6
-
- 1
+
+ 1
+ 1 1
+ 1 2 1
+ 1 3 3 1
+ 1 4 6 4 1
+ 1 5 10 10 5 1
+1 6 15 20 15 6 1
+
However, if we check the first one hundred rows, we will find that only 2361 of the 5050 entries are not divisible by 7.
-
-Find the number of entries which are not divisible by 7 in the first one billion (109) rows of Pascal's triangle.
## Instructions