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 A277298 #7 Oct 11 2016 18:41:15
%S A277298 1,2,76,5404,535410,66031704,9583782716,1584902128648,292586323812088,
%T A277298 59462699504146980,13171171610678351360,3155802303880338506184,
%U A277298 813045290972961285049576,224143228528852050484555760,65850557807967931843625040120,20543425063284611418233827507248,6784261706348459523065200262509390
%N A277298 Central terms of triangle A277295 in odd-indexed rows; a(n) = A277295(2*n-1,n-1).
%C A277298 G.f. G(x,y) of triangle A277295 satisfies:
%C A277298 (1) G(x,y) = x + G( y*G(x,y) + (1-y)*x, y)^2.
%C A277298 (2) G( x - y*G(x,y)^2, y) = x + (1-y)*G(x,y)^2.
%o A277298 (PARI) {A277295(n,k) = my(A=x); for(i=1, n, A = x + subst(A^2, x, y*A + (1-y)*x +x*O(x^n)) ); polcoeff(polcoeff(A,n,x),k,y)}
%o A277298 for(n=1,20,print1(A277295(2*n-1,n-1),", "))
%Y A277298 Cf. A277295, A277296, A277297, A277299.
%K A277298 nonn
%O A277298 1,2
%A A277298 _Paul D. Hanna_, Oct 11 2016