43839

Appears in sequences

• Starting from a(1)=2, a(n) = A028260(1+a(n-1)) if n is even, a(n) = A026424(a(n-1)) if n is odd.at n=14A160966
• G.f. A(x) satisfies: 1/(1 + x) = A(x)*A(x^2)^2*A(x^3)^3*A(x^4)^4* ... *A(x^k)^k* ...at n=39A307657
• a(n) is the number of distinct radii of circles passing through at least three points in a square grid of n X n points.at n=23A357301