45800

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=26A055503
• G.f.: 1 = 1/(1+x) + Sum_{n>=1} a(n)*C(2n,n-1)*x^n* Sum_{k>=0} C(2n+k,k)^2*(-x)^k.at n=5A181168
• The Wiener index of the comb-shaped graph |_|_|...|_| with 2n (n>=1) nodes. The Wiener index of a connected graph is the sum of the distances between all unordered pairs of vertices in the graph.at n=39A192023
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-2)^2, where a(0) = 2, a(1) = 3, b(0) = 1, and (a(n)) and (b(n)) are increasing complementary sequences.at n=16A296259