-1987

Appears in sequences

• a(n) = (-4*n^3 + 27*n^2 - 20*n + 3)/3.at n=14A161711
• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 405", based on the 5-celled von Neumann neighborhood.at n=23A271815