761880

Appears in sequences

• Number of -1..1 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having two, three, four or five distinct values for every i,j,k<=n.at n=16A211527
• a(n) = Sum_{k=0..n} binomial(2*n+2,k) * binomial(2*n-k,n-k).at n=7A386843