216985

Appears in sequences

• a(1) = 1, a(n+1) = a(n) + gpf(Sum_{i=1..n} a(i)), where gpf=A006530 (greatest prime factor).at n=28A080182
• Place a point on the integer coordinates, up to |n|, along all four axial directions on a Cartesian plane, and then join an infinite straight line between every pair of points: a(n) is the number of points where lines intersect in the resulting graph.at n=13A386559