Ludic numbers: Difference between revisions

Ludic numbers (view source)

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added whitespace to the task's preamble, used superscripts instead of quoted text ('nd, 'rd, 'th).

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rosettacode>Gerard Schildberger

Revision as of 03:46, 16 May 2016 (view source) rosettacode>Gerard Schildberger m (added a superscript th to a number.) ← Older edit		Revision as of 03:57, 16 May 2016 (view source) rosettacode>Gerard Schildberger m (added whitespace to the task's preamble, used superscripts instead of quoted text ('nd, 'rd, 'th).) Newer edit →
Line 3: [https://oeis.org/wiki/Ludic_numbers Ludic numbers]   are related to prime numbers as they are generated by a sieve quite like the [[Sieve of Eratosthenes]] is used to generate prime numbers. The first ludic number is   <span style="color:blue;font-weight:bold">1</span>. <br>To generate succeeding ludic numbers create an array of increasing integers starting from   2 :<code><span style="color:blue;font-weight:bold">2</span> 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ...</code> (Loop) * Take the first member of the resultant array as the next ludic number   <span style="color:blue;font-weight:bold">2</span>. * Remove every   '''2'<sup>nd</sup>'''   indexed item from the array (including the first). ::<code><span style="color:blue;font-weight:bold"><s>2</s></span> 3 <s>4</s> 5 <s>6</s> 7 <s>8</s> 9 <s>10</s> 11 <s>12</s> 13 <s>14</s> 15 <s>16</s> 17 <s>18</s> 19 <s>20</s> 21 <s>22</s> 23 <s>24</s> 25 <s>26</s> ...</code> * (Unrolling a few loops...) * Take the first member of the resultant array as the next ludic number   <span style="color:blue;font-weight:bold">3</span>. * Remove every   '''3'<sup>rd</sup>'''   indexed item from the array (including the first). ::<code><span style="color:blue;font-weight:bold"><s>3</s></span> 5 7 <s>9</s> 11 13 <s>15</s> 17 19 <s>21</s> 23 25 <s>27</s> 29 31 <s>33</s> 35 37 <s>39</s> 41 43 <s>45</s> 47 49 <s>51</s> ...</code> * Take the first member of the resultant array as the next ludic number   <span style="color:blue;font-weight:bold">5</span>. * Remove every   '''5'<sup>th</sup>'''   indexed item from the array (including the first). ::<code><span style="color:blue;font-weight:bold"><s>5</s></span> 7 11 13 17 <s>19</s> 23 25 29 31 <s>35</s> 37 41 43 47 <s>49</s> 53 55 59 61 <s>65</s> 67 71 73 77 ...</code> * Take the first member of the resultant array as the next ludic number   <span style="color:blue;font-weight:bold">7</span>. * Remove every   '''7'<sup>th</sup>'''   indexed item from the array (including the first). ::<code><span style="color:blue;font-weight:bold"><s>7</s></span> 11 13 17 23 25 29 <s>31</s> 37 41 43 47 53 55 <s>59</s> 61 67 71 73 77 83 <s>85</s> 89 91 97 ...</code> * ... * Take the first member of the current array as the next ludic number   <span style="color:blue;font-weight:bold">L</span>. * Remove every   '''L'<sup>th</sup>'''   indexed item from the array (including the first). * ... Line 30: * How many ludic numbers are there less than or equal to 1000? * Show the 2000..2005<sup>th</sup> ludic numbers. * A triplet is any three numbers     <big><math> x, </math>   <math> x+2, </math>   <math> x+6 </math> </big>     where all three numbers are also ludic numbers. <br> ~~Show all triplets of ludic numbers < 250 (~~;Stretch goal): Show all triplets of ludic numbers < 250. <br><br>