-2213

Appears in sequences

• a(n) = -n^2 + 9*n + 23.at n=52A126719
• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 123", based on the 5-celled von Neumann neighborhood.at n=25A270213
• a(n) = Sum_{k=0..n} (-1)^k*floor(phi^k), where phi is the golden ratio (A001622).at n=17A277752