24 lines
515 B
R
Executable file
24 lines
515 B
R
Executable file
library(numbers)
|
|
|
|
####
|
|
# limit: Obere Grenze für die Summe der Primzahltripel
|
|
#
|
|
# Gibt die Anzahl der einmaligen Primzahltripel
|
|
# bis zu einer oberen Grenze zurück.
|
|
####
|
|
euler87 <- function(limit) {
|
|
primes <- Primes(1, ceiling(limit^(1/2)))
|
|
|
|
x2 <- primes^2
|
|
x3 <- primes^3
|
|
x4 <- primes^4
|
|
x2 <- x2[x2 < limit]
|
|
x3 <- x3[x3 < limit]
|
|
x4 <- x4[x4 < limit]
|
|
|
|
x <- expand.grid(x2, x3, x4)
|
|
xSums <- rowSums(x)
|
|
length(unique(xSums[xSums < limit]))
|
|
}
|
|
|
|
system.time(print(euler87(5e7)))
|