626688

Appears in sequences

• Theta series of {D_10}* lattice.at n=25A008426
• a(1) = 1; a(n+1) = (Product_{k=1..n} a(k)) * Sum_{k=1..n} a(k).at n=5A057194
• Expansion of g.f. x/(1 + 4*x - 8*x^2).at n=9A174443
• a(n) = 4*a(n-1) + 8*a(n-2), with a(1)=0 and a(2)=1.at n=9A180222
• G.f. satisfies: A(x) = exp( Sum_{n>=1} [Sum_{k=0..2*n} A200536(n,k)^2 * x^k] / A(x)^n * x^n/n ), where A200536(n,k) is the coefficient of x^k in (1+3*x+2*x^2)^n.at n=25A200537
• Number of the Lipschitz quaternions in a reduced system modulo n.at n=33A227499
• (1/4) times the sum of the elements of all subsets of [n] whose sum is divisible by four.at n=17A309296
• Triangle read by rows: T(n, k) = (-1)^(n-k) * (2*n + 1)! * [y^(2*k)] [x^(2*n+1)] arctan(sec(x*y)*tanh(x)).at n=11A371687