1310464

Appears in sequences

• Expansion of (1-2x^2)/(1-2x-2x^2+2x^3).at n=16A052987
• a(n) = 20*a(n-1) - 64*a(n-2) for n > 1; a(0) = 1, a(1) = 19.at n=5A166965
• a(n) = Sum_{1 <= x_1, x_2 <= n} gcd(x_1, x_2, n)^4.at n=31A372926