An alternate proof of a theorem of J. Ewell (Q2785027)

This paper presents an alternative proof of a theorem of \textit{J. A. Ewell} [``Arithmetical consequences of a sextuple product identity'', Rocky Mt. J. Math. 25, 1287-1293 (1995; Zbl 0853.11029)] which states that the number of representations of a natural number \(n\) as a sum of four triangular numbers is equal to the sum of divisors of \(2n+1\). The proof is based on a well-known formula of Jacobi and a simple elementary argument.