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#!/usr/local/bin/Rscript
#
# See https://theweeklychallenge.org/blog/perl-weekly-challenge-147
#
#
# Run as: Rscript ch-1.r
#
suppressPackageStartupMessages (
library (gmp)
)
todo = c (2, 3, 5, 7)
cat (todo, "")
count = 20 - length (todo)
pow = 10
while (count > 0 && length (todo) > 0) {
new_todo = c ()
for (d in 1 : 9) {
for (p in todo) {
candidate = d * pow + p
if (isprime (candidate) > 0) {
cat (candidate, "")
count = count - 1
new_todo = c (new_todo, candidate)
if (count <= 0) {
break
}
}
if (count <= 0) {
break
}
}
if (count <= 0) {
break
}
}
pow = pow * 10
todo = new_todo
}
cat ("\n")
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