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 2016-09-10, 05:47 #1 MattcAnderson     "Matthew Anderson" Dec 2010 Oregon, USA 24×32×7 Posts A034856/ Hi Math People, I was exploring oeis.org. This is the Online Encyclopedia of integer sequences. oeis.org/A034856/ Many people have double checked this encyclopedia. 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. Probably I am wrong and the encyclopedia is right. I assume that binomial(n,k) = n!/(k!(n-k)!). Can someone else check this expression? Regards, Matt
2016-09-10, 07:25   #2
GP2

Sep 2003

1010000110012 Posts

Quote:
 Originally Posted by MattcAnderson 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

 2016-09-10, 14:20 #3 MattcAnderson     "Matthew Anderson" Dec 2010 Oregon, USA 24×32×7 Posts Thank you GP2. You are correct. Regards, Matt

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