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(This article was first published on <strong><a href="https://xianblog.wordpress.com/2017/08/10/sequence-riddle/"> R – Xi'an's Og</a></strong>, and kindly contributed to <a rel="nofollow" href="https://www.r-bloggers.com/">R-bloggers)</a> </div>
<p><strong><a rel="nofollow" href="https://xianblog.files.wordpress.com/2017/08/skye112.jpg" target="_blank"><img data-orig-file="https://xianblog.files.wordpress.com/2017/08/skye112.jpg?w=450&amp;h=197&amp;fit=450%2C197&amp;resize=450%2C197" data-orig-size="1648,720" data-medium-file="https://xianblog.files.wordpress.com/2017/08/skye112.jpg?w=450&amp;h=197&amp;fit=450%2C197&amp;resize=450%2C197?w=300" data-attachment-id="34051" data-image-meta="{" data-image-description="" src="https://xianblog.files.wordpress.com/2017/08/skye112.jpg?w=450&h=197&fit=450%2C197&resize=450%2C197" data-permalink="https://xianblog.wordpress.com/2017/08/10/sequence-riddle/olympus-digital-camera-311/" data-large-file="https://xianblog.files.wordpress.com/2017/08/skye112.jpg?w=450&amp;h=197&amp;fit=450%2C197&amp;resize=450%2C197?w=450" alt="" data-image-title="" sizes="(max-width: 450px) 100vw, 450px" data-comments-opened="1" class="wp-image-34051" data-recalc-dims="1"></a>T</strong>he riddle this week on <a rel="nofollow" href="https://fivethirtyeight.com/features/pick-a-number-any-number/" target="_blank">The Riddler</a> was about finding the largest sequence of integers between 1 and 100 such that each integer is only used once and always followed by a multiple or a factor. A basic R code searching at random [and programmed during a massive downpour on <a rel="nofollow" href="https://xianblog.wordpress.com/2017/07/31/sunset-on-sky-jatp/" target="_blank">Skye</a>] led to a solution of 69: <a rel="nofollow" href="https://xianblog.files.wordpress.com/2017/08/riddleranynum.jpg" target="_blank"><img data-orig-file="https://xianblog.files.wordpress.com/2017/08/riddleranynum.jpg?w=450&amp;h=450&amp;fit=450%2C450&amp;resize=450%2C450" data-orig-size="480,480" data-medium-file="https://xianblog.files.wordpress.com/2017/08/riddleranynum.jpg?w=450&amp;h=450&amp;fit=450%2C450&amp;resize=450%2C450?w=300" data-attachment-id="34052" data-image-meta="{" data-image-description="" src="https://xianblog.files.wordpress.com/2017/08/riddleranynum.jpg?w=450&h=450&fit=450%2C450&resize=450%2C450" data-permalink="https://xianblog.wordpress.com/2017/08/10/sequence-riddle/riddleranynum/" data-large-file="https://xianblog.files.wordpress.com/2017/08/riddleranynum.jpg?w=450&amp;h=450&amp;fit=450%2C450&amp;resize=450%2C450?w=450" alt="" data-image-title="riddleranynum" sizes="(max-width: 450px) 100vw, 450px" data-comments-opened="1" class="wp-image-34052" data-recalc-dims="1"></a></p>
<p>although there is no certainty this is the best p… And the solutions posted the next week showed sequences with length 77! [Interestingly, both posted solutions have a sequence starting with 87. And they seem to exploit the graph of connections between integers in a much more subtle way that my random exploration of subsequences.]</p>
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