Gessel, Ira M. and Larcombe, Peter J. (2009) “The sum 16nΣ2nk=04k( 1/2k)(-1/2k)(-2k 2n-k): A third proof of its closed form”, Utilitas Mathematica , 80. Available at: https://utilitasmathematica.com/index.php/Index/article/view/596 (Accessed: 8 May 2026).