> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/perl6-rosettacode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/perl6-rosettacode/programming_tasks/c/consecutive_primes_with_ascending_or_descending_differences.md).

# Consecutive primes with ascending or descending differences

```perl
use Math::Primesieve;
use Lingua::EN::Numbers;

my $sieve = Math::Primesieve.new;

my $limit = 1000000;

my @primes = $sieve.primes($limit);

sub runs (&op) {
    my $diff = 1;
    my $run = 1;

    my @diff = flat 1, (1..^@primes).map: {
        my $next = @primes[$_] - @primes[$_ - 1];
        if &op($next, $diff) { ++$run } else { $run = 1 }
        $diff = $next;
        $run;
    }

    my $max = max @diff;
    my @runs = @diff.grep: * == $max, :k;

    @runs.map( {
        my @run = (0..$max).reverse.map: -> $r { @primes[$_ - $r] }
        flat roundrobin(@run».&comma, @run.rotor(2 => -1).map({[R-] $_})».fmt('(%d)'));
    } ).join: "\n"
}

say "Longest run(s) of ascending prime gaps up to {comma $limit}:\n" ~ runs(&infix:«>»);

say "\nLongest run(s) of descending prime gaps up to {comma $limit}:\n" ~ runs(&infix:«<»);
```

#### Output:

```
Longest run(s) of ascending prime gaps up to 1,000,000:
128,981 (2) 128,983 (4) 128,987 (6) 128,993 (8) 129,001 (10) 129,011 (12) 129,023 (14) 129,037
402,581 (2) 402,583 (4) 402,587 (6) 402,593 (8) 402,601 (12) 402,613 (18) 402,631 (60) 402,691
665,111 (2) 665,113 (4) 665,117 (6) 665,123 (8) 665,131 (10) 665,141 (12) 665,153 (24) 665,177

Longest run(s) of descending prime gaps up to 1,000,000:
322,171 (22) 322,193 (20) 322,213 (16) 322,229 (8) 322,237 (6) 322,243 (4) 322,247 (2) 322,249
752,207 (44) 752,251 (12) 752,263 (10) 752,273 (8) 752,281 (6) 752,287 (4) 752,291 (2) 752,293
```