project-euler/Sidef/045 Triangular pentagonal and hexagonal.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# License: GPLv3
# Website: https://github.com/trizen

# It can be verified that T285 = P165 = H143 = 40755.
# Find the next triangle number that is also pentagonal and hexagonal.

# https://projecteuler.net/problem=45

# Runtime: 0.793s

for n in (144 .. Inf) {
    var h = n*(2*n - 1);
    if ((sqrt(1 + 24*h).inc %% 6) && (sqrt(1 + 8*h).dec %% 2)) {
        say h;
        break;
    }
}