%I #7 Mar 31 2012 13:21:27
%S 6,10,10,15,15,20,21,21,28,28,35,35,36,36,45,45,55,55,56,56,66,66,70,
%T 78,78,84,84,91,91,105,105,120,120,120,120,126,126,136,136,153,153,
%U 165,165,171,171,190,190,210,210,210,210,220,220,231,231,252,253,253,276,276,286
%N Binomial coefficients: C(n,k), 2 <= k <= n-2, sorted.
%F Sum_{n=1}^{infinity} 1/a(n) = 3/2. - _Franklin T. Adams-Watters_, Feb 28 2006
%Y Cf. A006987.
%K nonn
%O 1,1
%A _David W. Wilson_