%I #13 Mar 30 2012 18:37:32
%S 1,7,-54,827,-14012,259898,-5116318,105172355,-2234053248,48692954312,
%T -1083547583038,24527041757402,-563187320485774,13089954727844002,
%U -307442412559624318,7286803572075349907,-174090195438541310248,4188665368980014572652,-101416065009218889929998,2469364164437930871076352
%N Central terms in odd-indexed rows of triangle A200171.
%o (PARI) {a(n)=local(A=1+x); for(i=1, (2*n-1)^2+3*n, A=(1+x*A)*(1+x^(2*n-1)/(A+x*O(x^((2*n-1)^2+n))))); polcoeff(A, (2*n-1)^2+3*n-2)}
%Y Cf. A200171, A200172, A200173.
%K sign
%O 1,2
%A _Paul D. Hanna_, Nov 13 2011