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 A068554 #12 Nov 14 2016 00:27:18
%S A068554 -1,-2,-4,-4,24,236,1448,7640,37424,175436,798984,3565448,15672656,
%T A068554 68098936,293196944,1253020976,5322318944,22491436556,94632958664,
%U A068554 396682105256,1657418948624,6905368852136,28697991157424,119000162557136
%N A068554 a(n) = n*binomial(2n, n) - 4^n.
%C A068554 Known to be >= 0 for n>3.
%D A068554 Hojoo Lee, Posting to Number Theory List, Feb 18 2002.
%H A068554 Harvey P. Dale, <a href="/A068554/b068554.txt">Table of n, a(n) for n = 0..1000</a>
%F A068554 From _Robert Israel_, Nov 13 2016: (Start)
%F A068554 a(n) = A005430(n) - A000302(n).
%F A068554 G.f.: (2*x-sqrt(1-4*x))/(1-4*x)^(3/2).
%F A068554 a(n) = ((16*(n-2))*(2*n-5)*a(n-3)-(4*(8*n^2-23*n+18))*a(n-2)+(2*(5*n-4))*(n-1)*a(n-1))/(n*(n-1)). (End)
%p A068554 seq(n*binomial(2*n,n)-4^n,n=0..40); # _Robert Israel_, Nov 13 2016
%t A068554 Table[n*Binomial[2n,n]-4^n,{n,0,30}] (* _Harvey P. Dale_, Nov 17 2012 *)
%Y A068554 Cf. A000302, A005430.
%K A068554 sign
%O A068554 0,2
%A A068554 _N. J. A. Sloane_, Mar 23 2002