223517

Appears in sequences

• Take n points in general position in the plane; draw all the (infinite) straight lines joining them; sequence gives number of connected regions formed.at n=38A055503
• a(n) = Sum_{k=0..floor(n/6)} (7*k+1) * binomial(2*n-5*k+1,n-6*k)/(2*n-5*k+1).at n=12A390481