a(n) = (tan(1*Pi/9))^(2*n) + (tan(2*Pi/9))^(2*n) + (tan(3*Pi/9))^(2*n) + (tan(4*Pi/9))^(2*n).

A353410

a(n) = (tan(1*Pi/9))^(2*n) + (tan(2*Pi/9))^(2*n) + (tan(3*Pi/9))^(2*n) + (tan(4*Pi/9))^(2*n).

Terms

    a(0) =4a(1) =36a(2) =1044a(3) =33300a(4) =1070244a(5) =34420356a(6) =1107069876a(7) =35607151476

External references