A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.
R Language Code
The Prime Function
prime = function(n){ n = as.integer(n) if(n > 1e8) stop(“n too large”) primes = re...

It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square.
9 = 7 + 212
15 = 7 + 222
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Starting with 1 and spiralling anticlockwise in the following way, a square spiral with side length 7 is formed.
37 36 35 34 33 32 31
38 17 16 15 14 13 30
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