311466

Appears in sequences

• Number of n-vertex, 2-edge multigraphs that are not nesting. Number of n-vertex, 2-edge multigraphs that are not crossing.at n=37A326278
• Numbers k for which k and k^2 are digitally balanced numbers in base 3 (A049354).at n=23A372147
• a(n) = Sum_{k=1..n} tan(k*Pi/(1+2*n))^4.at n=18A377858