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- #!/usr/bin/perl
- # Daniel "Trizen" Șuteu
- # Date: 15 October 2017
- # https://github.com/trizen
- # Runtime: 0.008s
- # https://projecteuler.net/problem=138
- # Simpler solution:
- # L(n) = fibonacci(6*n + 3) / 2
- # See also:
- # https://oeis.org/A007805
- use 5.010;
- use strict;
- use warnings;
- my $n = 1;
- my $diff = 1;
- my $prev = 1;
- my $sum = 0;
- foreach my $k (1 .. 12) {
- $n = $prev * (17 + 1) - $diff;
- $sum += $n;
- $diff = $prev;
- $prev = $n;
- say "L($k) = $n";
- }
- say "\nSum: ", $sum;
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