a(n) = Sum_{k=0..n} tan(k*Pi/(1+2*n))^(2*n).

A376777

a(n) = Sum_{k=0..n} tan(k*Pi/(1+2*n))^(2*n).

Terms

    a(0) =1a(1) =3a(2) =90a(3) =7077a(4) =1070244a(5) =264893255a(6) =97371674686

External references