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%I #4 Oct 12 2012 14:40:23
%S -1,5,-17,-229,853,12113,-46061,-674761,38733269,-150113729,
%T 8829861373,134484418361,-525740249453,-8058251350417,486561579496253,
%U -29557651813108141,116325817932650581,-7111675770821993117,-110606189396709847609
%N Central numbers in triangle A103728.
%C a(n) given by the formula below is indeed an integer because A103728 is an integer triangle.
%F a(n)= A103728(n, b(n)), n>=2, with b(n):=(p(n)-1)/2=A005097(n-1) and p(n)= A000040(n) (n-th prime number).
%F a(n)=(1+((-1)^b(n))*2*b(n)*binomial(2*b(n), b(n)))/(2*b(n)+1), n>=2, with b(n) defined above.
%K sign,easy
%O 2,2
%A _Wolfdieter Lang_, Mar 24 2005