what is the general equation for this series / pattern? - MathOverflow [closed] most recent 30 from http://mathoverflow.net 2013-05-24T09:40:47Z http://mathoverflow.net/feeds/question/81849 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/81849/what-is-the-general-equation-for-this-series-pattern what is the general equation for this series / pattern? Rodrigo 2011-11-25T05:12:15Z 2011-11-25T05:12:15Z <pre><code> for an arbitrary word, how can we derive "i" given the pattern below? for a (i = 1) a for ab (i = 3) a ab b for abc (i = 6) a ab abc b bc c for abcd (i = 10) a ab abc abcd b bc bcd c cd d for abcde (i = 15) a ab abc abcd abcde b bc bcd bcde c cd cde d de e </code></pre>