40846domain: NAppears in sequencesG.f. satisfies: A(x) = x + A(x^2/(1-x)^2).at n=14A119685G.f. satisfies: 1 = Sum_{n>=0} (-x)^(n*(n+1)/2) * A(x)^(n+1).at n=10A193111a(n) = Sum_{1 <= i <= j <= k <= m <= n} gcd(i,j,k,m).at n=28A344992