This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A185251 #17 May 09 2018 10:17:57
%S A185251 0,0,2,3,16,25,96,154,512,837,2560,4246,12288,20618,57344,97140,
%T A185251 262144,447661,1179648,2028478,5242880,9070110,23068672,40122028,
%U A185251 100663296,175913250,436207616,765561564,1879048192,3310623412,8053063680,14238676712,34359738368
%N A185251 a(n) = Sum_{k=0..floor(n/2)} k*binomial(n,k).
%H A185251 G. C. Greubel, <a href="/A185251/b185251.txt">Table of n, a(n) for n = 0..1000</a>
%p A185251 seq(n*2^(n-2) - `if`(type(n,even), 0, binomial(n-1, (n-1)/2)*n/2) ,n=0..32); # _Mark van Hoeij_, May 12 2013
%t A185251 Table[Sum[k Binomial[n, k], {k, 0, Floor[n/2]}], {n, 0, 40}] (* _Harvey P. Dale_, Nov 25 2012 *)
%o A185251 (PARI) a(n)=sum(k=0,n\2,k*binomial(n,k))
%K A185251 nonn,easy
%O A185251 0,3
%A A185251 _M. F. Hasler_, Jan 24 2012