201215

Appears in sequences

• a(n) = Sum_{k=0..n} T(n,k), where T is the array defined in A025177.at n=12A025191
• y-values in the solution to 13*x^2 - 12 = y^2.at n=9A199405
• Decimal representation of the diagonal from the origin to the corner of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 201", based on the 5-celled von Neumann neighborhood.at n=17A286671