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- #!/usr/bin/ruby
- # https://rosettacode.org/wiki/Brazilian_numbers
- func is_Brazilian_prime(q) {
- static L = Set()
- static M = 0
- return true if L.has(q)
- return false if (q < M)
- var N = (q<500 ? 1000 : 2*q)
- for K in (primes(3, ilog2(N+1))) {
- for n in (2 .. iroot(N-1, K-1)) {
- var p = (n**K - 1)/(n-1)
- L << p if (p<N && p.is_prime)
- }
- }
- M = (L.max \\ 0)
- return L.has(q)
- }
- func is_Brazilian(n) {
- if (!n.is_prime) {
- n.is_square || return (n>6)
- var m = n.isqrt
- return (m>3 && (!m.is_prime || m==11))
- }
- is_Brazilian_prime(n)
- }
- with (20) {|n|
- say "First #{n} Brazilian numbers:"
- say (^Inf -> lazy.grep(is_Brazilian).first(n))
- say "\nFirst #{n} odd Brazilian numbers:"
- say (^Inf -> lazy.grep(is_Brazilian).grep{.is_odd}.first(n))
- say "\nFirst #{n} prime Brazilian numbers"
- say (^Inf -> lazy.grep(is_Brazilian).grep{.is_prime}.first(n))
- }
- assert_eq(is_Brazilian.first(20), [7, 8, 10, 12, 13, 14, 15, 16, 18, 20, 21, 22, 24, 26, 27, 28, 30, 31, 32, 33])
- assert_eq({.is_odd && is_Brazilian(_)}.first(20), [7, 13, 15, 21, 27, 31, 33, 35, 39, 43, 45, 51, 55, 57, 63, 65, 69, 73, 75, 77])
- assert_eq({.is_prime && is_Brazilian(_)}.first(20), [7, 13, 31, 43, 73, 127, 157, 211, 241, 307, 421, 463, 601, 757, 1093, 1123, 1483, 1723, 2551, 2801])
- assert_eq(is_Brazilian.nth(1e4), 11364)
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