The Weekly Challenge - 144

Monday, Dec 20, 2021| Tags: Perl, Raku










09. TASK #1: Semiprime

10. TASK #2: Ulam Sequence


Apology for the delay in the release of the weekly challenge.

I would like to start the week with a good news, the fund for the 1000 days T-shirt campaign is now £1029.74, thanks to all sponsors, specially last minute surprise sponsor, Pete Sergeant.

I am just waiting to get the response from the remaining champions before I move to next stage of the campaign. As of today, I have received 32 confirmations out of 53. I know it is festive season, everyone is busy with family. I would appreciate if you could please take a few moments and reply to my email asap. For more updates, please check out the blog post.

Welcome back, Mark Senn, after a long break and thanks for the contributions. Also thanks for introducing a new language, Wolfram.

We had bonus review this week by our in-house Perl reviewer, Colin Crain. Thank you for the quality reviews every week.

Talking about bonus, I am back with the YouTube Videos after nearly 5 months. I had days off the work, so I did it 5 videos back to back. I hope you like the video. If you do please share with your friends. Thank You.

If you want to checkout my previous videos then please do visit my YouTube Channel. As of today, I have got 145 subscribers, not a big number but big enough to keep me motivated. Thank you once again all the subscribers.

The Weekly Challenge - 143 (Task #1: Calculator)

The Weekly Challenge - 141 (Task #1: Number Divisors)

The Weekly Challenge - 140 (Task #1: Add Binary)

The Weekly Challenge - 138 (Task #1: Workdays)

The Weekly Challenge - 137 (Task #1: Long Year)

Advent Calendar 2021

Small improvement to the Advent Calendar, it now shows the topic and author on mouse over day image. I hope you like it.

Day 13: Pythagorean Triples by W. Luis Mochan.

Day 14: Minesweeper Game by Luca Ferrari.

Day 15: Spiral Matrix by Lubos Kolouch.

Day 16: Bell Numbers by Jaldhar H. Vyas.

Day 17: Magical Matrix by Walt Mankowski.

Day 18: Isomorphic Strings by Andrew Shitov.

Day 19: Triplet Sum by Jorg Sommrey.

Day 20: Workdays by Steven Wilson.

Blogs with Creative Title

1. Stealthy Calculations by Adam Russell.

2. Stealthy Calculator with Raku and Perl by Arne Sommer.

3. Ninja Numbers Hiding In Trees: The Weekly Challenge #143 by Dave Jacoby

4. Perl Weekly Challenge 143: stealthing the grammars! by Luca Ferrari.

5. The Weekly Challenge 143: Stealthy Calculator by Roger Bell_West.

Let us share some interesting stats from the GitHub repository.

1. Commits: 22,092 (+135)

2. Pull Requests: 5,385 (+25)

3. Contributors: 183

4. Fork: 234

5. Stars: 118 (+2)

Last but not least, I would like to thank each and every member for their support and encouragement.

Our solo sponsor Pete Sergeant has been a great support to keep us motivated. We are lucky that he agreed to continue the journey with us in the year 2021. I would like to personally thank Pete and his entire team for their generosity. It would be great if we could add few more to sponsor the prize money so that we could go back and declare weekly champions as we have done in the past. I hope and wish this will become possible in 2021. The amount doesn’t have to be huge. However, it would be nice to show off bunch of supporters. If an organisation comes forward and supports us then that would be the ultimate achievement.


Quick recap of “The Weekly Challenge - 143” by Mohammad S Anwar.


Please check out Perl solutions review of the “The Weekly Challenge - 138” and “The Weekly Challenge - 139” by Colin Crain.

If you missed any past reviews then please check out the collection.


If you missed any past reviews then please check out the collection.


Please take a look at the charts showing interesting data.

I would like to THANK every member of the team for their valuable suggestions. Please do share your experience with us.


Please find out How to contribute?, if you have any doubts.

Please try the excellent tool EZPWC created by respected member Saif Ahmed of Team PWC.


Please checkout the guest contributions for the Week #143.

Please find past solutions by respected guests. Please share your creative solutions in other languages.

TASK #1 › Semiprime

Submitted by: Mohammad S Anwar

Write a script to generate all Semiprime number <= 100.

For more information about Semiprime, please checkout the wikipedia page.

In mathematics, a semiprime is a natural number that is the product of exactly two prime numbers. The two primes in the product may equal each other, so the semiprimes include the squares of prime numbers.


10 is Semiprime as 10 = 2 x 5
15 is Semiprime as 15 = 3 x 5

TASK #2 › Ulam Sequence

Submitted by: Mohammad S Anwar

You are given two positive numbers, $u and $v.

Write a script to generate Ulam Sequence having at least 10 Ulam numbers where $u and $v are the first 2 Ulam numbers.

For more information about Ulam Sequence, please checkout the website.

The standard Ulam sequence (the (1, 2)-Ulam sequence) starts with U1 = 1 and U2 = 2. Then for n > 2, Un is defined to be the smallest integer that is the sum of two distinct earlier terms in exactly one way and larger than all earlier terms.

Example 1

Input: $u = 1, $v = 2
Output: 1, 2, 3, 4, 6, 8, 11, 13, 16, 18

Example 2

Input: $u = 2, $v = 3
Output: 2, 3, 5, 7, 8, 9, 13, 14, 18, 19

Example 3

Input: $u = 2, $v = 5
Output: 2, 5, 7, 9, 11, 12, 13, 15, 19, 23

Last date to submit the solution 23:59 (UK Time) Sunday 26th December 2021.


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