Gessel, Ira M., Larcombe, Peter J. The sum 16nΣ2nk=04k( 1/2k)(-1/2k)(-2k 2n-k): A third proof of its closed form. A Canadian journal of applied mathematics, computer science and statistics [Internet]. 2009 Sep. 9 [cited 2026 May 8];80. Available from: https://utilitasmathematica.com/index.php/Index/article/view/596