August 27, 2024

P43 - A list of Goldbach compositions (2)

Given a range of integers by its lower and upper limit, print a list of all even numbers and their Goldbach composition.

scala

scala> printGoldbachList(9 to 20)
10 = 3 + 7
12 = 5 + 7
14 = 3 + 11
16 = 3 + 13
18 = 5 + 13
20 = 3 + 17

In most cases, if an even number is written as the sum of two prime numbers, one of them is very small.  Very rarely, the primes are both bigger than, say, 50.  Try to find out how many such cases there are in the range 2..3000.

Example (minimum value of 50 for the primes):

scala

scala> printGoldbachListLimited(1 to 2000, 50)
992 = 73 + 919
1382 = 61 + 1321
1856 = 67 + 1789
1928 = 61 + 1867
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