Thread: A034856/
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Old 2016-09-10, 07:25   #2
GP2
 
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Sep 2003

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Quote:
Originally Posted by MattcAnderson View Post
oeis.org/A034856/

I read that for A034856, a(n) reduces to n*(n+3)/2 - 1.

When I work it through, I reach the expression n*(n-1)/2 -1.
Code:
binomial(n+1, 2) + (n − 1)

    n*(n+1)     2*(n−1)
=   -------  +  -------
       2           2

    n*n + 1*n + 2*n − 2
=   -------------------
             2

    n*(n+3) − 2
=   -----------
         2

    n*(n+3)
=   -------  −  1
       2
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