In mathematics, Catalan's constant G, is defined by G = β = ∑ n = 0 ∞ n 2 = 1 1 2 − 1 3 2 + 1 5 2 − 1 7 2 + 1 9 2 − ⋯, {\displaystyle G=\beta =\sum _{n=0}^{\infty }{\frac {^{n}}{^{2}}}={\frac {1}{1^{2}}}-{\frac {1}{3^{2}}}+{\frac {1}{5^{2}}}-{\frac {1}{7^{2}}}+{\frac {1}{9^{2}}}-\cdots,} where β is the Dirichlet beta function. Wikipedia